Merge branch 'decompile_battle_9' of https://github.com/DizzyEggg/pokeemerald into DizzyEggg-decompile_battle_9

asm/battle_controller_opponent.s

@@ -5212,7 +5212,7 @@ sub_8061F90: @ 8061F90
 	thumb_func_start sub_8061F9C
 sub_8061F9C: @ 8061F9C
 	push {lr}
-	bl sub_8063880
+	bl AI_TrySwitchOrUseItem
 	bl OpponentBufferExecCompleted
 	pop {r0}
 	bx r0
@@ -5243,7 +5243,7 @@ sub_8061FB8: @ 8061FB8
 	movs r0, 0x1
 	movs r1, 0xA
 _08061FD6:
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 _08061FDA:
 	bl OpponentBufferExecCompleted
 	b _08062156
@@ -5347,7 +5347,7 @@ _0806209C:
 	movs r0, 0x1
 	movs r1, 0xA
 	adds r2, r4, 0
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	b _08061FDA
 	.pool
 _080620C4:
@@ -5378,7 +5378,7 @@ _080620C6:
 	movs r0, 0x1
 	movs r1, 0xA
 	adds r2, r4, 0
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	b _08062152
 	.pool
 _08062108:
@@ -5401,7 +5401,7 @@ _08062108:
 	orrs r2, r4
 	movs r0, 0x1
 	movs r1, 0xA
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	b _08062152
 	.pool
 _0806213C:
@@ -5413,7 +5413,7 @@ _0806213C:
 	orrs r2, r4
 	movs r0, 0x1
 	movs r1, 0xA
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 _08062152:
 	bl OpponentBufferExecCompleted
 _08062156:
@@ -5456,7 +5456,7 @@ sub_8062188: @ 8062188
 	ldrb r0, [r1]
 	cmp r0, 0x6
 	bne _08062254
-	bl sub_8063A90
+	bl GetMostSuitableMonToSwitchInto
 	lsls r0, 24
 	lsrs r4, r0, 24
 	cmp r4, 0x6

asm/battle_controller_player.s

@@ -226,7 +226,7 @@ _0805764C:
 	movs r0, 0x1
 	movs r1, 0x3
 	movs r2, 0
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	b _080577C2
 _08057658:
 	movs r0, 0x20
@@ -393,7 +393,7 @@ _080577B2:
 	movs r1, 0xC
 _080577BC:
 	movs r2, 0
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 _080577C2:
 	bl PlayerBufferExecCompleted
 	b _080577E8
@@ -518,7 +518,7 @@ _080578A0:
 	orrs r2, r0
 	movs r0, 0x1
 	movs r1, 0xA
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	ldrb r0, [r4]
 	movs r1, 0x1
 	bl dp11b_obj_free
@@ -1086,7 +1086,7 @@ _08057E14:
 _08057E1C:
 	movs r0, 0x1
 	movs r1, 0xA
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	bl PlayerBufferExecCompleted
 	b _08057F9E
 	.pool
@@ -3413,7 +3413,7 @@ _080591FE:
 	lsrs r2, 16
 	movs r0, 0x1
 	movs r1, 0xB
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	strb r5, [r4]
 	bl battle_type_is_double
 	lsls r0, 24
@@ -3686,7 +3686,7 @@ _08059430:
 	lsrs r2, 16
 	movs r0, 0x1
 	movs r1, 0xB
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	strb r5, [r4]
 	ldr r0, =sub_8059544
 	str r0, [r6]
@@ -4291,14 +4291,14 @@ _08059A2C:
 	movs r0, 0x1
 	movs r1, 0xE
 	movs r2, 0
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	b _08059A76
 	.pool
 _08059A6C:
 	movs r0, 0x1
 	movs r1, 0xD
 	movs r2, 0
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 _08059A76:
 	bl PlayerBufferExecCompleted
 _08059A7A:
@@ -8658,7 +8658,7 @@ sub_805C158: @ 805C158
 	lsrs r2, 16
 	movs r0, 0x1
 	movs r1, 0xA
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	bl PlayerBufferExecCompleted
 _0805C194:
 	pop {r0}
@@ -9378,7 +9378,7 @@ sub_805C80C: @ 805C80C
 	movs r0, 0x1
 	movs r1, 0
 	movs r2, 0
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	bl PlayerBufferExecCompleted
 	pop {r0}
 	bx r0

asm/battle_controller_player_partner.s

@@ -645,7 +645,7 @@ _081BB2E2:
 	lsrs r2, 16
 	movs r0, 0x1
 	movs r1, 0xB
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	strb r5, [r4]
 	bl battle_type_is_double
 	lsls r0, 24
@@ -918,7 +918,7 @@ _081BB514:
 	lsrs r2, 16
 	movs r0, 0x1
 	movs r1, 0xB
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	strb r5, [r4]
 	ldr r0, =sub_81BB628
 	str r0, [r6]
@@ -4990,7 +4990,7 @@ sub_81BDAA0: @ 81BDAA0
 	thumb_func_start sub_81BDAAC
 sub_81BDAAC: @ 81BDAAC
 	push {lr}
-	bl sub_8063880
+	bl AI_TrySwitchOrUseItem
 	bl PlayerPartnerBufferExecCompleted
 	pop {r0}
 	bx r0
@@ -5068,7 +5068,7 @@ _081BDB3C:
 	orrs r2, r5
 	movs r0, 0x1
 	movs r1, 0xA
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	bl PlayerPartnerBufferExecCompleted
 	pop {r4-r6}
 	pop {r0}
@@ -5087,7 +5087,7 @@ sub_81BDB70: @ 81BDB70
 	thumb_func_start sub_81BDB7C
 sub_81BDB7C: @ 81BDB7C
 	push {r4-r6,lr}
-	bl sub_8063A90
+	bl GetMostSuitableMonToSwitchInto
 	lsls r0, 24
 	lsrs r4, r0, 24
 	cmp r4, 0x6

asm/battle_controller_recorded_opponent.s

@@ -4754,7 +4754,7 @@ sub_8188EF0: @ 8188EF0
 	lsrs r1, 24
 	movs r0, 0x1
 	movs r2, 0
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	bl RecordedOpponentBufferExecCompleted
 	pop {r0}
 	bx r0
@@ -4785,7 +4785,7 @@ sub_8188F20: @ 8188F20
 	lsrs r2, 16
 	movs r0, 0x1
 	movs r1, 0xA
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	b _08188F6C
 	.pool
 _08188F48:
@@ -4803,7 +4803,7 @@ _08188F48:
 	orrs r2, r4
 	movs r0, 0x1
 	movs r1, 0xA
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 _08188F6C:
 	bl RecordedOpponentBufferExecCompleted
 	pop {r4,r5}

asm/battle_controller_recorded_player.s

@@ -4861,7 +4861,7 @@ sub_818C49C: @ 818C49C
 	lsrs r1, 24
 	movs r0, 0x1
 	movs r2, 0
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	bl RecordedPlayerBufferExecCompleted
 _0818C4C6:
 	pop {r0}
@@ -4897,7 +4897,7 @@ _0818C508:
 	lsrs r1, 24
 	movs r0, 0x1
 	movs r2, 0
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	bl RecordedPlayerBufferExecCompleted
 _0818C522:
 	pop {r0}
@@ -4929,7 +4929,7 @@ sub_818C538: @ 818C538
 	lsrs r2, 16
 	movs r0, 0x1
 	movs r1, 0xA
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	b _0818C584
 	.pool
 _0818C560:
@@ -4947,7 +4947,7 @@ _0818C560:
 	orrs r2, r4
 	movs r0, 0x1
 	movs r1, 0xA
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 _0818C584:
 	bl RecordedPlayerBufferExecCompleted
 	pop {r4,r5}

asm/battle_controller_safari.s

@@ -103,13 +103,13 @@ _0815942A:
 	movs r1, 0x7
 _0815942E:
 	movs r2, 0
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	b _08159440
 _08159436:
 	movs r0, 0x1
 	movs r1, 0x8
 	movs r2, 0
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 _08159440:
 	bl SafariBufferExecCompleted
 	b _0815954E

asm/battle_controller_wally.s

@@ -153,7 +153,7 @@ _081684CE:
 	movs r1, 0x9
 _081684E4:
 	movs r2, 0
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	bl WallyBufferExecCompleted
 	ldr r1, [r4]
 	adds r1, 0x94
@@ -208,7 +208,7 @@ _08168540:
 	movs r0, 0x1
 	movs r1, 0x1
 	movs r2, 0
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	bl WallyBufferExecCompleted
 _08168564:
 	pop {r4,r5}
@@ -3777,7 +3777,7 @@ _0816A550:
 	lsls r2, 1
 	movs r0, 0x1
 	movs r1, 0xA
-	bl dp01_build_cmdbuf_x21_a_bb
+	bl EmitCmd_x21
 	bl WallyBufferExecCompleted
 _0816A574:
 	pop {r4}

asm/rom3.s

@@ -3259,8 +3259,8 @@ _0803413E:
 	.pool
 	thumb_func_end sub_8034110
 
-	thumb_func_start dp01_build_cmdbuf_x21_a_bb
+	thumb_func_start EmitCmd_x21
-dp01_build_cmdbuf_x21_a_bb: @ 8034158
+EmitCmd_x21: @ 8034158
 	push {r4,lr}
 	adds r4, r1, 0
 	lsls r0, 24
@@ -3280,7 +3280,7 @@ dp01_build_cmdbuf_x21_a_bb: @ 8034158
 	pop {r0}
 	bx r0
 	.pool
-	thumb_func_end dp01_build_cmdbuf_x21_a_bb
+	thumb_func_end EmitCmd_x21
 
 	thumb_func_start dp01_build_cmdbuf_x22_a_three_bytes
 dp01_build_cmdbuf_x22_a_three_bytes: @ 8034184

include/battle.h

@@ -5,6 +5,7 @@
 #include "battle_util.h"
 #include "battle_script_commands.h"
 #include "battle_2.h"
+#include "battle_ai_switch_items.h"
 
 /*
     Banks are a name given to what could be called a 'battlerId' or 'monControllerId'.
@@ -476,7 +477,7 @@ struct BattleHistory
     struct UsedMoves usedMoves[BATTLE_BANKS_COUNT];
     u8 abilities[BATTLE_BANKS_COUNT];
     u8 itemEffects[BATTLE_BANKS_COUNT];
-    u16 TrainerItems[BATTLE_BANKS_COUNT];
+    u16 trainerItems[BATTLE_BANKS_COUNT];
     u8 itemsNo;
 };
 
@@ -632,8 +633,8 @@ struct BattleStruct
     void (*savedCallback)(void);
     u16 usedHeldItems[BATTLE_BANKS_COUNT];
     u8 field_C0[4];
-    u8 field_C4[2];
+    u8 AI_itemType[2];
-    u8 field_C6[2];
+    u8 AI_itemFlags[2];
     u16 choicedMove[BATTLE_BANKS_COUNT];
     u16 changedItems[BATTLE_BANKS_COUNT];
     u8 intimidateBank;

include/battle_ai_switch_items.h

@@ -0,0 +1,17 @@
+#ifndef GUARD_BATTLE_AI_SWITCH_ITEMS_H
+#define GUARD_BATTLE_AI_SWITCH_ITEMS_H
+
+enum
+{
+    AI_ITEM_FULL_RESTORE = 1,
+    AI_ITEM_HEAL_HP,
+    AI_ITEM_CURE_CONDITION,
+    AI_ITEM_X_STAT,
+    AI_ITEM_GUARD_SPECS,
+    AI_ITEM_NOT_RECOGNIZABLE
+};
+
+void AI_TrySwitchOrUseItem(void);
+u8 GetMostSuitableMonToSwitchInto(void);
+
+#endif // GUARD_BATTLE_AI_SWITCH_ITEMS_H

include/battle_controllers.h

@@ -84,5 +84,6 @@ void Emit_x32(u8 bufferId);
 void EmitPrintString(u8 bufferId, u16 stringId);
 void EmitResetActionMoveSelection(u8 bufferId, u8 caseId);
 void EmitBallThrow(u8 bufferId, u8 caseId);
+void EmitCmd_x21(u8 bufferId, u8 arg1, u16 arg2);
 
 #endif // GUARD_BATTLE_CONTROLLERS_H

include/battle_script_commands.h

@@ -43,7 +43,7 @@
 
 void AI_CalcDmg(u8 bankAtk, u8 bankDef);
 u8 TypeCalc(u16 move, u8 bankAtk, u8 bankDef);
-u8 AI_TypeCalc(u16 move, u16 species, u8 ability);
+u8 AI_TypeCalc(u16 move, u16 targetSpecies, u8 targetAbility);
 u8 BankGetTurnOrder(u8 bank);
 void SetMoveEffect(bool8 primary, u8 certain);
 void BattleDestroyCursorAt(u8 cursorPosition);

include/pokemon.h

@@ -642,6 +642,7 @@ void UpdatePartyPokerusTime(u16 days);
 void PartySpreadPokerus(struct Pokemon *party);
 s8 GetMonFlavourRelation(struct Pokemon *mon, u8 a2);
 s8 GetFlavourRelationByPersonality(u32 personality, u8 a2);
+u8 GetItemEffectParamOffset(u16 itemId, u8 effectByte, u8 effectBit);
 
 #include "sprite.h"
 

include/pokemon_item_effects.h

@@ -3,6 +3,60 @@
 
 #include "pokemon.h"
 
+// TODO once pokemon item effects is decompiled
+/*
+struct PokemonItemEffect
+{
+    //field 0
+    u8 xAtk : 4; // x1, x2, x4, x8 = xF
+    u8 field_0_x10 : 1; // x10
+    u8 critRatioUp : 1; // x20
+    u8 field_0_x40 : 1; // x40
+    u8 cureInfatuation : 1; // x80
+
+    /*field 1
+    u8 xSpeed : 4; // x1, x2, x4, x8 = xF
+    u8 xDefense : 4; // x10, x20, x40, xF0
+
+    /*field 2
+    u8 xSpAtk : 4; // x1, x2, x4, x8 = xF
+    u8 xAccuracy : 4; // x10, x20, x40, xF0
+
+    /*field 3
+    u8 cureConfusion : 1; // x1
+    u8 cureParalysis : 1; // x2
+    u8 cureFreeze : 1; // x4
+    u8 cureBurn : 1; // x8
+    u8 curePoison : 1; // x10
+    u8 cureSleep : 1; // x20
+    u8 field_3_x40 : 1; // x40
+    u8 cantLowerStats : 1; // x80
+
+    /*field 4
+    u8 hpEv : 1; // x1
+    u8 attackEv : 1; // x2
+    u8 healHp : 1; // x4
+    u8 field_4_x8 : 1; // x8
+    u8 field_4_x10 : 1; // x10
+    u8 ppUp : 1; // x20
+    u8 levelUp : 1; // x40
+    u8 evolutionStone : 1; // x80
+
+    /*field 5
+    u8 defEv:  1; // x1
+    u8 speedEv : 1; // x2
+    u8 spDefEv : 1; // x4
+    u8 spAtkEv : 1; // x8
+    u8 ppMax : 1; // x10
+    u8 field_5_x20 : 1; // x20
+    u8 field_5_x40 : 1; // x40
+    u8 field_5_x80 : 1; // x80
+
+    /*field 6
+    u8 value;
+};
+*/
+
 bool8 ExecuteTableBasedItemEffect(struct Pokemon *mon, u16 itemId, u8 partyId, u8 monMoveIndex, u8 a5);
 
 #endif // GUARD_POKEMON_ITEM_EFFECTS

ld_script.txt

@@ -64,7 +64,7 @@ SECTIONS {
         asm/battle_controller_player.o(.text);
         asm/battle_7.o(.text);
         asm/battle_controller_opponent.o(.text);
-        asm/battle_9.o(.text);
+        src/battle_ai_switch_items.o(.text);
         asm/battle_controller_linkopponent.o(.text);
         src/pokemon_1.o(.text);
         asm/pokemon_1.o(.text);

src/battle_2.c

@@ -5324,30 +5324,30 @@ static void HandleAction_UseItem(void)
     {
         gBattleScripting.bank = gBankAttacker;
 
-        switch (*(gBattleStruct->field_C4 + (gBankAttacker >> 1)))
+        switch (*(gBattleStruct->AI_itemType + (gBankAttacker >> 1)))
         {
-        case 1:
+        case AI_ITEM_FULL_RESTORE:
-        case 2:
+        case AI_ITEM_HEAL_HP:
             break;
-        case 3:
+        case AI_ITEM_CURE_CONDITION:
             gBattleCommunication[MULTISTRING_CHOOSER] = 0;
-            if (*(gBattleStruct->field_C6 + gBankAttacker / 2) & 1)
+            if (*(gBattleStruct->AI_itemFlags + gBankAttacker / 2) & 1)
             {
-                if (*(gBattleStruct->field_C6 + gBankAttacker / 2) & 0x3E)
+                if (*(gBattleStruct->AI_itemFlags + gBankAttacker / 2) & 0x3E)
                     gBattleCommunication[MULTISTRING_CHOOSER] = 5;
             }
             else
             {
-                while (!(*(gBattleStruct->field_C6 + gBankAttacker / 2) & 1))
+                while (!(*(gBattleStruct->AI_itemFlags + gBankAttacker / 2) & 1))
                 {
-                    *(gBattleStruct->field_C6 + gBankAttacker / 2) >>= 1;
+                    *(gBattleStruct->AI_itemFlags + gBankAttacker / 2) >>= 1;
                     gBattleCommunication[MULTISTRING_CHOOSER]++;
                 }
             }
             break;
-        case 4:
+        case AI_ITEM_X_STAT:
             gBattleCommunication[MULTISTRING_CHOOSER] = 4;
-            if (*(gBattleStruct->field_C6 + (gBankAttacker >> 1)) & 0x80)
+            if (*(gBattleStruct->AI_itemFlags + (gBankAttacker >> 1)) & 0x80)
             {
                 gBattleCommunication[MULTISTRING_CHOOSER] = 5;
             }
@@ -5356,9 +5356,9 @@ static void HandleAction_UseItem(void)
                 PREPARE_STAT_BUFFER(gBattleTextBuff1, STAT_ATK)
                 PREPARE_STRING_BUFFER(gBattleTextBuff2, 0xD2)
 
-                while (!((*(gBattleStruct->field_C6 + (gBankAttacker >> 1))) & 1))
+                while (!((*(gBattleStruct->AI_itemFlags + (gBankAttacker >> 1))) & 1))
                 {
-                    *(gBattleStruct->field_C6 + gBankAttacker / 2) >>= 1;
+                    *(gBattleStruct->AI_itemFlags + gBankAttacker / 2) >>= 1;
                     gBattleTextBuff1[2]++;
                 }
 
@@ -5366,7 +5366,7 @@ static void HandleAction_UseItem(void)
                 gBattleScripting.animArg2 = 0;
             }
             break;
-        case 5:
+        case AI_ITEM_GUARD_SPECS:
             if (gBattleTypeFlags & BATTLE_TYPE_DOUBLE)
                 gBattleCommunication[MULTISTRING_CHOOSER] = 2;
             else
@@ -5374,7 +5374,7 @@ static void HandleAction_UseItem(void)
             break;
         }
 
-        gBattlescriptCurrInstr = gUnknown_082DBD3C[*(gBattleStruct->field_C4 + gBankAttacker / 2)];
+        gBattlescriptCurrInstr = gUnknown_082DBD3C[*(gBattleStruct->AI_itemType + gBankAttacker / 2)];
     }
     gCurrentActionFuncId = ACTION_RUN_BATTLESCRIPT;
 }

src/battle_ai_script_commands.c

@@ -331,7 +331,7 @@ void BattleAI_HandleItemUseBeforeAISetup(u8 defaultScoreMoves)
         {
             if (gTrainers[gTrainerBattleOpponent_A].items[i] != 0)
             {
-                gBattleResources->battleHistory->TrainerItems[gBattleResources->battleHistory->itemsNo] = gTrainers[gTrainerBattleOpponent_A].items[i];
+                gBattleResources->battleHistory->trainerItems[gBattleResources->battleHistory->itemsNo] = gTrainers[gTrainerBattleOpponent_A].items[i];
                 gBattleResources->battleHistory->itemsNo++;
             }
         }

src/battle_ai_switch_items.c

@@ -0,0 +1,951 @@
+#include "global.h"
+#include "battle.h"
+#include "battle_controllers.h"
+#include "abilities.h"
+#include "moves.h"
+#include "pokemon.h"
+#include "species.h"
+#include "rng.h"
+#include "util.h"
+#include "items.h"
+#include "pokemon_item_effects.h"
+
+extern u8 gActiveBank;
+extern u8 gAbsentBankFlags;
+extern u32 gBattleTypeFlags;
+extern u32 gStatuses3[BATTLE_BANKS_COUNT];
+extern struct BattlePokemon gBattleMons[BATTLE_BANKS_COUNT];
+extern u16 gBattlePartyID[BATTLE_BANKS_COUNT];
+extern u16 gUnknown_02024250[BATTLE_BANKS_COUNT];
+extern u8 gUnknown_02024270[BATTLE_BANKS_COUNT];
+extern u16 gDynamicBasePower;
+extern u8 gBattleMoveFlags;
+extern u8 gCritMultiplier;
+extern s32 gBattleMoveDamage;
+
+extern const struct BattleMove gBattleMoves[];
+extern const struct BaseStats gBaseStats[];
+extern const u8 gTypeEffectiveness[];
+extern const u8 * const gItemEffectTable[]; // todo: fix once struct is declared
+
+// this file's functions
+static bool8 HasSuperEffectiveMoveAgainstOpponents(bool8 noRng);
+static bool8 FindMonWithFlagsAndSuperEffective(u8 flags, u8 moduloPercent);
+static bool8 ShouldUseItem(void);
+
+static bool8 ShouldSwitchIfPerishSong(void)
+{
+    if (gStatuses3[gActiveBank] & STATUS3_PERISH_SONG
+        && gDisableStructs[gActiveBank].perishSong1 == 0)
+    {
+        *(gBattleStruct->field_294 + gActiveBank) = 6;
+        EmitCmd_x21(1, 2, 0);
+        return TRUE;
+    }
+
+    return FALSE;
+}
+
+static bool8 ShouldSwitchIfWonderGuard(void)
+{
+    u8 opposingIdentity;
+    u8 opposingBank;
+    u8 moveFlags;
+    s32 i, j;
+    s32 firstId;
+    s32 lastId; // + 1
+    struct Pokemon *party = NULL;
+    u16 move;
+
+    if (gBattleTypeFlags & BATTLE_TYPE_DOUBLE)
+        return FALSE;
+
+    opposingIdentity = GetBankIdentity(gActiveBank) ^ BIT_SIDE;
+
+    if (gBattleMons[GetBankByIdentity(opposingIdentity)].ability != ABILITY_WONDER_GUARD)
+        return FALSE;
+
+    // check if pokemon has a super effective move
+    for (opposingBank = GetBankByIdentity(opposingIdentity), i = 0; i < 4; i++)
+    {
+        move = gBattleMons[gActiveBank].moves[i];
+        if (move == MOVE_NONE)
+            continue;
+
+        moveFlags = AI_TypeCalc(move, gBattleMons[opposingBank].species, gBattleMons[opposingBank].ability);
+        if (moveFlags & MOVESTATUS_SUPEREFFECTIVE)
+            return FALSE;
+    }
+
+    // get party information
+    if (gBattleTypeFlags & (BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_x800000))
+    {
+        if ((gActiveBank & BIT_MON) == 0)
+            firstId = 0, lastId = 3;
+        else
+            firstId = 3, lastId = 6;
+    }
+    else
+    {
+        firstId = 0, lastId = 6;
+    }
+
+    if (GetBankSide(gActiveBank) == SIDE_PLAYER)
+        party = gPlayerParty;
+    else
+        party = gEnemyParty;
+
+    // find a pokemon in the party that has a super effective move
+    for (i = firstId; i < lastId; i++)
+    {
+        if (GetMonData(&party[i], MON_DATA_HP) == 0)
+            continue;
+        if (GetMonData(&party[i], MON_DATA_SPECIES2) == SPECIES_NONE)
+            continue;
+        if (GetMonData(&party[i], MON_DATA_SPECIES2) == SPECIES_EGG)
+            continue;
+        if (i == gBattlePartyID[gActiveBank])
+            continue;
+
+        GetMonData(&party[i], MON_DATA_SPECIES); // unused return value
+        GetMonData(&party[i], MON_DATA_ALT_ABILITY); // unused return value
+
+        for (opposingBank = GetBankByIdentity(opposingIdentity), j = 0; j < 4; j++)
+        {
+            move = GetMonData(&party[i], MON_DATA_MOVE1 + j);
+            if (move == MOVE_NONE)
+                continue;
+
+            moveFlags = AI_TypeCalc(move, gBattleMons[opposingBank].species, gBattleMons[opposingBank].ability);
+            if (moveFlags & MOVESTATUS_SUPEREFFECTIVE && Random() % 3 < 2)
+            {
+                // we found a mon
+                *(gBattleStruct->field_294 + gActiveBank) = i;
+                EmitCmd_x21(1, 2, 0);
+                return TRUE;
+            }
+        }
+    }
+
+    return FALSE; // at this point there is not a single pokemon in the party that has a super effective move against a pokemon with wonder guard
+}
+
+static bool8 FindMonThatAbsorbsOpponentsMove(void)
+{
+    u8 bankIn1, bankIn2;
+    u8 absorbingTypeAbility;
+    s32 firstId;
+    s32 lastId; // + 1
+    struct Pokemon *party;
+    s32 i;
+
+    if (HasSuperEffectiveMoveAgainstOpponents(TRUE) && Random() % 3 != 0)
+        return FALSE;
+    if (gUnknown_02024250[gActiveBank] == 0)
+        return FALSE;
+    if (gUnknown_02024250[gActiveBank] == 0xFFFF)
+        return FALSE;
+    if (gBattleMoves[gUnknown_02024250[gActiveBank]].power == 0)
+        return FALSE;
+
+    if (gBattleTypeFlags & BATTLE_TYPE_DOUBLE)
+    {
+        bankIn1 = gActiveBank;
+        if (gAbsentBankFlags & gBitTable[GetBankByIdentity(GetBankIdentity(gActiveBank) ^ BIT_MON)])
+            bankIn2 = gActiveBank;
+        else
+            bankIn2 = GetBankByIdentity(GetBankIdentity(gActiveBank) ^ BIT_MON);
+    }
+    else
+    {
+        bankIn1 = gActiveBank;
+        bankIn2 = gActiveBank;
+    }
+
+    if (gBattleMoves[gUnknown_02024250[gActiveBank]].type == TYPE_FIRE)
+        absorbingTypeAbility = ABILITY_FLASH_FIRE;
+    else if (gBattleMoves[gUnknown_02024250[gActiveBank]].type == TYPE_WATER)
+        absorbingTypeAbility = ABILITY_WATER_ABSORB;
+    else if (gBattleMoves[gUnknown_02024250[gActiveBank]].type == TYPE_ELECTRIC)
+        absorbingTypeAbility = ABILITY_VOLT_ABSORB;
+    else
+        return FALSE;
+
+    if (gBattleMons[gActiveBank].ability == absorbingTypeAbility)
+        return FALSE;
+
+    if (gBattleTypeFlags & (BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_x800000))
+    {
+        if ((gActiveBank & BIT_MON) == 0)
+            firstId = 0, lastId = 3;
+        else
+            firstId = 3, lastId = 6;
+    }
+    else
+    {
+        firstId = 0, lastId = 6;
+    }
+
+    if (GetBankSide(gActiveBank) == SIDE_PLAYER)
+        party = gPlayerParty;
+    else
+        party = gEnemyParty;
+
+    for (i = firstId; i < lastId; i++)
+    {
+        u16 species;
+        u8 monAbility;
+
+        if (GetMonData(&party[i], MON_DATA_HP) == 0)
+            continue;
+        if (GetMonData(&party[i], MON_DATA_SPECIES2) == SPECIES_NONE)
+            continue;
+        if (GetMonData(&party[i], MON_DATA_SPECIES2) == SPECIES_EGG)
+            continue;
+        if (i == gBattlePartyID[bankIn1])
+            continue;
+        if (i == gBattlePartyID[bankIn2])
+            continue;
+        if (i == *(gBattleStruct->field_5C + bankIn1))
+            continue;
+        if (i == *(gBattleStruct->field_5C + bankIn2))
+            continue;
+
+        species = GetMonData(&party[i], MON_DATA_SPECIES);
+        if (GetMonData(&party[i], MON_DATA_ALT_ABILITY) != 0)
+            monAbility = gBaseStats[species].ability2;
+        else
+            monAbility = gBaseStats[species].ability1;
+
+        if (absorbingTypeAbility == monAbility && Random() & 1)
+        {
+            // we found a mon
+            *(gBattleStruct->field_294 + gActiveBank) = i;
+            EmitCmd_x21(1, 2, 0);
+            return TRUE;
+        }
+    }
+
+    return FALSE;
+}
+
+static bool8 ShouldSwitchIfNaturalCure(void)
+{
+    if (!(gBattleMons[gActiveBank].status1 & STATUS_SLEEP))
+        return FALSE;
+    if (gBattleMons[gActiveBank].ability != ABILITY_NATURAL_CURE)
+        return FALSE;
+    if (gBattleMons[gActiveBank].hp < gBattleMons[gActiveBank].maxHP / 2)
+        return FALSE;
+
+    if ((gUnknown_02024250[gActiveBank] == 0 || gUnknown_02024250[gActiveBank] == 0xFFFF) && Random() & 1)
+    {
+        *(gBattleStruct->field_294 + gActiveBank) = 6;
+        EmitCmd_x21(1, 2, 0);
+        return TRUE;
+    }
+    else if (gBattleMoves[gUnknown_02024250[gActiveBank]].power == 0 && Random() & 1)
+    {
+        *(gBattleStruct->field_294 + gActiveBank) = 6;
+        EmitCmd_x21(1, 2, 0);
+        return TRUE;
+    }
+
+    if (FindMonWithFlagsAndSuperEffective(MOVESTATUS_NOTAFFECTED, 1))
+        return TRUE;
+    if (FindMonWithFlagsAndSuperEffective(MOVESTATUS_NOTVERYEFFECTIVE, 1))
+        return TRUE;
+    if (Random() & 1)
+    {
+        *(gBattleStruct->field_294 + gActiveBank) = 6;
+        EmitCmd_x21(1, 2, 0);
+        return TRUE;
+    }
+
+    return FALSE;
+}
+
+static bool8 HasSuperEffectiveMoveAgainstOpponents(bool8 noRng)
+{
+    u8 opposingIdentity;
+    u8 opposingBank;
+    s32 i;
+    u8 moveFlags;
+    u16 move;
+
+    opposingIdentity = GetBankIdentity(gActiveBank) ^ BIT_SIDE;
+    opposingBank = GetBankByIdentity(opposingIdentity);
+
+    if (!(gAbsentBankFlags & gBitTable[opposingBank]))
+    {
+        for (i = 0; i < 4; i++)
+        {
+            move = gBattleMons[gActiveBank].moves[i];
+            if (move == MOVE_NONE)
+                continue;
+
+            moveFlags = AI_TypeCalc(move, gBattleMons[opposingBank].species, gBattleMons[opposingBank].ability);
+            if (moveFlags & MOVESTATUS_SUPEREFFECTIVE)
+            {
+                if (noRng)
+                    return TRUE;
+                if (Random() % 10 != 0)
+                    return TRUE;
+            }
+        }
+    }
+    if (!(gBattleTypeFlags & BATTLE_TYPE_DOUBLE))
+        return FALSE;
+
+    opposingBank = GetBankByIdentity(opposingIdentity ^ BIT_MON);
+
+    if (!(gAbsentBankFlags & gBitTable[opposingBank]))
+    {
+        for (i = 0; i < 4; i++)
+        {
+            move = gBattleMons[gActiveBank].moves[i];
+            if (move == MOVE_NONE)
+                continue;
+
+            moveFlags = AI_TypeCalc(move, gBattleMons[opposingBank].species, gBattleMons[opposingBank].ability);
+            if (moveFlags & MOVESTATUS_SUPEREFFECTIVE)
+            {
+                if (noRng)
+                    return TRUE;
+                if (Random() % 10 != 0)
+                    return TRUE;
+            }
+        }
+    }
+
+    return FALSE;
+}
+
+static bool8 AreStatsRaised(void)
+{
+    u8 buffedStatsValue = 0;
+    s32 i;
+
+    for (i = 0; i < BATTLE_STATS_NO; i++)
+    {
+        if (gBattleMons[gActiveBank].statStages[i] > 6)
+            buffedStatsValue += gBattleMons[gActiveBank].statStages[i] - 6;
+    }
+
+    return (buffedStatsValue > 3);
+}
+
+static bool8 FindMonWithFlagsAndSuperEffective(u8 flags, u8 moduloPercent)
+{
+    u8 bankIn1, bankIn2;
+    s32 firstId;
+    s32 lastId; // + 1
+    struct Pokemon *party;
+    s32 i, j;
+    u16 move;
+    u8 moveFlags;
+
+    if (gUnknown_02024250[gActiveBank] == 0)
+        return FALSE;
+    if (gUnknown_02024250[gActiveBank] == 0xFFFF)
+        return FALSE;
+    if (gUnknown_02024270[gActiveBank] == 0xFF)
+        return FALSE;
+    if (gBattleMoves[gUnknown_02024250[gActiveBank]].power == 0)
+        return FALSE;
+
+    if (gBattleTypeFlags & BATTLE_TYPE_DOUBLE)
+    {
+        bankIn1 = gActiveBank;
+        if (gAbsentBankFlags & gBitTable[GetBankByIdentity(GetBankIdentity(gActiveBank) ^ BIT_MON)])
+            bankIn2 = gActiveBank;
+        else
+            bankIn2 = GetBankByIdentity(GetBankIdentity(gActiveBank) ^ BIT_MON);
+    }
+    else
+    {
+        bankIn1 = gActiveBank;
+        bankIn2 = gActiveBank;
+    }
+
+    if (gBattleTypeFlags & (BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_x800000))
+    {
+        if ((gActiveBank & BIT_MON) == 0)
+            firstId = 0, lastId = 3;
+        else
+            firstId = 3, lastId = 6;
+    }
+    else
+    {
+        firstId = 0, lastId = 6;
+    }
+
+    if (GetBankSide(gActiveBank) == SIDE_PLAYER)
+        party = gPlayerParty;
+    else
+        party = gEnemyParty;
+
+    for (i = firstId; i < lastId; i++)
+    {
+        u16 species;
+        u8 monAbility;
+
+        if (GetMonData(&party[i], MON_DATA_HP) == 0)
+            continue;
+        if (GetMonData(&party[i], MON_DATA_SPECIES2) == SPECIES_NONE)
+            continue;
+        if (GetMonData(&party[i], MON_DATA_SPECIES2) == SPECIES_EGG)
+            continue;
+        if (i == gBattlePartyID[bankIn1])
+            continue;
+        if (i == gBattlePartyID[bankIn2])
+            continue;
+        if (i == *(gBattleStruct->field_5C + bankIn1))
+            continue;
+        if (i == *(gBattleStruct->field_5C + bankIn2))
+            continue;
+
+        species = GetMonData(&party[i], MON_DATA_SPECIES);
+        if (GetMonData(&party[i], MON_DATA_ALT_ABILITY) != 0)
+            monAbility = gBaseStats[species].ability2;
+        else
+            monAbility = gBaseStats[species].ability1;
+
+        moveFlags = AI_TypeCalc(gUnknown_02024250[gActiveBank], species, monAbility);
+        if (moveFlags & flags)
+        {
+            bankIn1 = gUnknown_02024270[gActiveBank];
+
+            for (j = 0; j < 4; j++)
+            {
+                move = GetMonData(&party[i], MON_DATA_MOVE1 + j);
+                if (move == 0)
+                    continue;
+
+                moveFlags = AI_TypeCalc(move, gBattleMons[bankIn1].species, gBattleMons[bankIn1].ability);
+                if (moveFlags & MOVESTATUS_SUPEREFFECTIVE && Random() % moduloPercent == 0)
+                {
+                    *(gBattleStruct->field_294 + gActiveBank) = i;
+                    EmitCmd_x21(1, 2, 0);
+                    return TRUE;
+                }
+            }
+        }
+    }
+
+    return FALSE;
+}
+
+static bool8 ShouldSwitch(void)
+{
+    u8 bankIn1, bankIn2;
+    u8 *activeBankPtr; // needed to match
+    s32 firstId;
+    s32 lastId; // + 1
+    struct Pokemon *party;
+    s32 i;
+    s32 availableToSwitch;
+
+    if (gBattleMons[*(activeBankPtr = &gActiveBank)].status2 & (STATUS2_WRAPPED | STATUS2_ESCAPE_PREVENTION))
+        return FALSE;
+    if (gStatuses3[gActiveBank] & STATUS3_ROOTED)
+        return FALSE;
+    if (AbilityBattleEffects(ABILITYEFFECT_CHECK_OTHER_SIDE, gActiveBank, ABILITY_SHADOW_TAG, 0, 0))
+        return FALSE;
+    if (AbilityBattleEffects(ABILITYEFFECT_CHECK_OTHER_SIDE, gActiveBank, ABILITY_ARENA_TRAP, 0, 0))
+        return FALSE; // misses the flying or levitate check
+    if (AbilityBattleEffects(ABILITYEFFECT_FIELD_SPORT, 0, ABILITY_MAGNET_PULL, 0, 0))
+    {
+        if (gBattleMons[gActiveBank].type1 == TYPE_STEEL)
+            return FALSE;
+        if (gBattleMons[gActiveBank].type2 == TYPE_STEEL)
+            return FALSE;
+    }
+    if (gBattleTypeFlags & BATTLE_TYPE_ARENA)
+        return FALSE;
+
+    availableToSwitch = 0;
+    if (gBattleTypeFlags & BATTLE_TYPE_DOUBLE)
+    {
+        bankIn1 = *activeBankPtr;
+        if (gAbsentBankFlags & gBitTable[GetBankByIdentity(GetBankIdentity(*activeBankPtr) ^ BIT_MON)])
+            bankIn2 = *activeBankPtr;
+        else
+            bankIn2 = GetBankByIdentity(GetBankIdentity(*activeBankPtr) ^ BIT_MON);
+    }
+    else
+    {
+        bankIn1 = *activeBankPtr;
+        bankIn2 = *activeBankPtr;
+    }
+
+    if (gBattleTypeFlags & (BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_x800000))
+    {
+        if ((gActiveBank & BIT_MON) == 0)
+            firstId = 0, lastId = 3;
+        else
+            firstId = 3, lastId = 6;
+    }
+    else
+    {
+        firstId = 0, lastId = 6;
+    }
+
+    if (GetBankSide(gActiveBank) == SIDE_PLAYER)
+        party = gPlayerParty;
+    else
+        party = gEnemyParty;
+
+    for (i = firstId; i < lastId; i++)
+    {
+        if (GetMonData(&party[i], MON_DATA_HP) == 0)
+            continue;
+        if (GetMonData(&party[i], MON_DATA_SPECIES2) == SPECIES_NONE)
+            continue;
+        if (GetMonData(&party[i], MON_DATA_SPECIES2) == SPECIES_EGG)
+            continue;
+        if (i == gBattlePartyID[bankIn1])
+            continue;
+        if (i == gBattlePartyID[bankIn2])
+            continue;
+        if (i == *(gBattleStruct->field_5C + bankIn1))
+            continue;
+        if (i == *(gBattleStruct->field_5C + bankIn2))
+            continue;
+
+        availableToSwitch++;
+    }
+
+    if (availableToSwitch == 0)
+        return FALSE;
+    if (ShouldSwitchIfPerishSong())
+        return TRUE;
+    if (ShouldSwitchIfWonderGuard())
+        return TRUE;
+    if (FindMonThatAbsorbsOpponentsMove())
+        return TRUE;
+    if (ShouldSwitchIfNaturalCure())
+        return TRUE;
+    if (HasSuperEffectiveMoveAgainstOpponents(FALSE))
+        return FALSE;
+    if (AreStatsRaised())
+        return FALSE;
+    if (FindMonWithFlagsAndSuperEffective(MOVESTATUS_NOTAFFECTED, 2)
+        || FindMonWithFlagsAndSuperEffective(MOVESTATUS_NOTVERYEFFECTIVE, 3))
+        return TRUE;
+
+    return FALSE;
+}
+
+void AI_TrySwitchOrUseItem(void)
+{
+    struct Pokemon *party;
+    u8 bankIn1, bankIn2;
+    s32 firstId;
+    s32 lastId; // + 1
+    u8 bankIdentity = GetBankIdentity(gActiveBank);
+
+    if (GetBankSide(gActiveBank) == SIDE_PLAYER)
+        party = gPlayerParty;
+    else
+        party = gEnemyParty;
+
+    if (gBattleTypeFlags & BATTLE_TYPE_TRAINER)
+    {
+        if (ShouldSwitch())
+        {
+            if (*(gBattleStruct->field_294 + gActiveBank) == 6)
+            {
+                s32 monToSwitchId = GetMostSuitableMonToSwitchInto();
+                if (monToSwitchId == 6)
+                {
+                    if (!(gBattleTypeFlags & BATTLE_TYPE_DOUBLE))
+                    {
+                        bankIn1 = GetBankByIdentity(bankIdentity);
+                        bankIn2 = bankIn1;
+                    }
+                    else
+                    {
+                        bankIn1 = GetBankByIdentity(bankIdentity);
+                        bankIn2 = GetBankByIdentity(bankIdentity ^ BIT_MON);
+                    }
+
+                    if (gBattleTypeFlags & (BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_x800000))
+                    {
+                        if ((gActiveBank & BIT_MON) == 0)
+                            firstId = 0, lastId = 3;
+                        else
+                            firstId = 3, lastId = 6;
+                    }
+                    else
+                    {
+                        firstId = 0, lastId = 6;
+                    }
+
+                    for (monToSwitchId = firstId; monToSwitchId < lastId; monToSwitchId++)
+                    {
+                        if (GetMonData(&party[monToSwitchId], MON_DATA_HP) == 0)
+                            continue;
+                        if (monToSwitchId == gBattlePartyID[bankIn1])
+                            continue;
+                        if (monToSwitchId == gBattlePartyID[bankIn2])
+                            continue;
+                        if (monToSwitchId == *(gBattleStruct->field_5C + bankIn1))
+                            continue;
+                        if (monToSwitchId == *(gBattleStruct->field_5C + bankIn2))
+                            continue;
+
+                        break;
+                    }
+                }
+
+                *(gBattleStruct->field_294 + gActiveBank) = monToSwitchId;
+            }
+
+            *(gBattleStruct->field_5C + gActiveBank) = *(gBattleStruct->field_294 + gActiveBank);
+            return;
+        }
+        else if (ShouldUseItem())
+        {
+            return;
+        }
+    }
+
+    EmitCmd_x21(1, 0, (gActiveBank ^ BIT_SIDE) << 8);
+}
+
+#define TYPE_FORESIGHT  0xFE
+#define TYPE_ENDTABLE   0xFF
+
+static void ModulateByTypeEffectiveness(u8 atkType, u8 defType1, u8 defType2, u8 *var)
+{
+    s32 i = 0;
+
+    while (gTypeEffectiveness[i] != TYPE_ENDTABLE)
+    {
+        if (gTypeEffectiveness[i] == TYPE_FORESIGHT)
+        {
+            i += 3;
+            continue;
+        }
+        else if (gTypeEffectiveness[i] == atkType)
+        {
+            // check type1
+            if (gTypeEffectiveness[i + 1] == defType1)
+                *var = (*var * gTypeEffectiveness[i + 2]) / 10;
+            // check type2
+            if (gTypeEffectiveness[i + 1] == defType2 && defType1 != defType2)
+                *var = (*var * gTypeEffectiveness[i + 2]) / 10;
+        }
+        i += 3;
+    }
+}
+
+u8 GetMostSuitableMonToSwitchInto(void)
+{
+    u8 opposingBank;
+    u8 bestDmg; // note : should be changed to u32 for obvious reasons
+    u8 bestMonId;
+    u8 bankIn1, bankIn2;
+    s32 firstId;
+    s32 lastId; // + 1
+    struct Pokemon *party;
+    s32 i, j;
+    u8 invalidMons;
+    u16 move;
+
+    if (*(gBattleStruct->field_5C + gActiveBank) != 6)
+        return *(gBattleStruct->field_5C + gActiveBank);
+    if (gBattleTypeFlags & BATTLE_TYPE_ARENA)
+        return gBattlePartyID[gActiveBank] + 1;
+
+    if (gBattleTypeFlags & BATTLE_TYPE_DOUBLE)
+    {
+        bankIn1 = gActiveBank;
+        if (gAbsentBankFlags & gBitTable[GetBankByIdentity(GetBankIdentity(gActiveBank) ^ BIT_MON)])
+            bankIn2 = gActiveBank;
+        else
+            bankIn2 = GetBankByIdentity(GetBankIdentity(gActiveBank) ^ BIT_MON);
+
+        // UB: It considers the opponent only player's side even though it can battle alongside player;
+        opposingBank = Random() & BIT_MON;
+        if (gAbsentBankFlags & gBitTable[opposingBank])
+            opposingBank ^= BIT_MON;
+    }
+    else
+    {
+        opposingBank = GetBankByIdentity(GetBankIdentity(gActiveBank) ^ BIT_SIDE);
+        bankIn1 = gActiveBank;
+        bankIn2 = gActiveBank;
+    }
+
+    if (gBattleTypeFlags & (BATTLE_TYPE_TWO_OPPONENTS | BATTLE_TYPE_x800000))
+    {
+        if ((gActiveBank & BIT_MON) == 0)
+            firstId = 0, lastId = 3;
+        else
+            firstId = 3, lastId = 6;
+    }
+    else
+    {
+        firstId = 0, lastId = 6;
+    }
+
+    if (GetBankSide(gActiveBank) == SIDE_PLAYER)
+        party = gPlayerParty;
+    else
+        party = gEnemyParty;
+
+    invalidMons = 0;
+
+    while (invalidMons != 0x3F) // all mons are invalid
+    {
+        bestDmg = 0;
+        bestMonId = 6;
+        // find the mon which type is the most suitable offensively
+        for (i = firstId; i < lastId; i++)
+        {
+            u16 species = GetMonData(&party[i], MON_DATA_SPECIES);
+            if (species != SPECIES_NONE
+                && GetMonData(&party[i], MON_DATA_HP) != 0
+                && !(gBitTable[i] & invalidMons)
+                && gBattlePartyID[bankIn1] != i
+                && gBattlePartyID[bankIn2] != i
+                && i != *(gBattleStruct->field_5C + bankIn1)
+                && i != *(gBattleStruct->field_5C + bankIn2))
+            {
+                u8 type1 = gBaseStats[species].type1;
+                u8 type2 = gBaseStats[species].type2;
+                u8 typeDmg = 10;
+                ModulateByTypeEffectiveness(gBattleMons[opposingBank].type1, type1, type2, &typeDmg);
+                ModulateByTypeEffectiveness(gBattleMons[opposingBank].type2, type1, type2, &typeDmg);
+                if (bestDmg < typeDmg)
+                {
+                    bestDmg = typeDmg;
+                    bestMonId = i;
+                }
+            }
+            else
+            {
+                invalidMons |= gBitTable[i];
+            }
+        }
+
+        // ok, we know the mon has the right typing but does it have at least one super effective move?
+        if (bestMonId != 6)
+        {
+            for (i = 0; i < 4; i++)
+            {
+                move = GetMonData(&party[bestMonId], MON_DATA_MOVE1 + i);
+                if (move != MOVE_NONE && TypeCalc(move, gActiveBank, opposingBank) & MOVESTATUS_SUPEREFFECTIVE)
+                    break;
+            }
+
+            if (i != 4)
+                return bestMonId; // has both the typing and at least one super effective move
+
+            invalidMons |= gBitTable[bestMonId]; // sorry buddy, we want something better
+        }
+        else
+        {
+            invalidMons = 0x3F; // no viable mon to switch
+        }
+    }
+
+    gDynamicBasePower = 0;
+    gBattleStruct->dynamicMoveType = 0;
+    gBattleScripting.dmgMultiplier = 1;
+    gBattleMoveFlags = 0;
+    gCritMultiplier = 1;
+    bestDmg = 0;
+    bestMonId = 6;
+
+    // if we couldn't find the best mon in terms of typing, find the one that deals most damage
+    for (i = firstId; i < lastId; i++)
+    {
+        if ((u16)(GetMonData(&party[i], MON_DATA_SPECIES)) == SPECIES_NONE)
+            continue;
+        if (GetMonData(&party[i], MON_DATA_HP) == 0)
+            continue;
+        if (gBattlePartyID[bankIn1] == i)
+            continue;
+        if (gBattlePartyID[bankIn2] == i)
+            continue;
+        if (i == *(gBattleStruct->field_5C + bankIn1))
+            continue;
+        if (i == *(gBattleStruct->field_5C + bankIn2))
+            continue;
+
+        for (j = 0; j < 4; j++)
+        {
+            move = GetMonData(&party[i], MON_DATA_MOVE1 + j);
+            gBattleMoveDamage = 0;
+            if (move != MOVE_NONE && gBattleMoves[move].power != 1)
+            {
+                AI_CalcDmg(gActiveBank, opposingBank);
+                TypeCalc(move, gActiveBank, opposingBank);
+            }
+            if (bestDmg < gBattleMoveDamage)
+            {
+                bestDmg = gBattleMoveDamage;
+                bestMonId = i;
+            }
+        }
+    }
+
+    return bestMonId;
+}
+
+// TODO: use PokemonItemEffect struct instead of u8 once it's documented
+static u8 GetAI_ItemType(u8 itemId, const u8 *itemEffect) // NOTE: should take u16 as item Id argument
+{
+    if (itemId == ITEM_FULL_RESTORE)
+        return AI_ITEM_FULL_RESTORE;
+    if (itemEffect[4] & 4)
+        return AI_ITEM_HEAL_HP;
+    if (itemEffect[3] & 0x3F)
+        return AI_ITEM_CURE_CONDITION;
+    if (itemEffect[0] & 0x3F || itemEffect[1] != 0 || itemEffect[2] != 0)
+        return AI_ITEM_X_STAT;
+    if (itemEffect[3] & 0x80)
+        return AI_ITEM_GUARD_SPECS;
+
+    return AI_ITEM_NOT_RECOGNIZABLE;
+}
+
+static bool8 ShouldUseItem(void)
+{
+    struct Pokemon *party;
+    s32 i;
+    u8 validMons = 0;
+    bool8 shouldUse = FALSE;
+
+    if (gBattleTypeFlags & BATTLE_TYPE_INGAME_PARTNER && GetBankIdentity(gActiveBank) == IDENTITY_PLAYER_MON2)
+        return FALSE;
+
+    if (GetBankSide(gActiveBank) == SIDE_PLAYER)
+        party = gPlayerParty;
+    else
+        party = gEnemyParty;
+
+    for (i = 0; i < 6; i++)
+    {
+        if (GetMonData(&party[i], MON_DATA_HP) != 0
+            && GetMonData(&party[i], MON_DATA_SPECIES2) != SPECIES_NONE
+            && GetMonData(&party[i], MON_DATA_SPECIES2) != SPECIES_EGG)
+        {
+            validMons++;
+        }
+    }
+
+    for (i = 0; i < 4; i++)
+    {
+        u16 item;
+        const u8 *itemEffects;
+        u8 paramOffset;
+        u8 bankSide;
+
+        if (i != 0 && validMons > (gBattleResources->battleHistory->itemsNo - i) + 1)
+            continue;
+        item = gBattleResources->battleHistory->trainerItems[i];
+        if (item == ITEM_NONE)
+            continue;
+        if (gItemEffectTable[item - 13] == NULL)
+            continue;
+
+        if (item == ITEM_ENIGMA_BERRY)
+            itemEffects = gSaveBlock1Ptr->enigmaBerry.itemEffect;
+        else
+            itemEffects = gItemEffectTable[item - 13];
+
+        *(gBattleStruct->AI_itemType + gActiveBank / 2) = GetAI_ItemType(item, itemEffects);
+
+        switch (*(gBattleStruct->AI_itemType + gActiveBank / 2))
+        {
+        case AI_ITEM_FULL_RESTORE:
+            if (gBattleMons[gActiveBank].hp >= gBattleMons[gActiveBank].maxHP / 4)
+                break;
+            if (gBattleMons[gActiveBank].hp == 0)
+                break;
+            shouldUse = TRUE;
+            break;
+        case AI_ITEM_HEAL_HP:
+            paramOffset = GetItemEffectParamOffset(item, 4, 4);
+            if (paramOffset == 0)
+                break;
+            if (gBattleMons[gActiveBank].hp == 0)
+                break;
+            if (gBattleMons[gActiveBank].hp < gBattleMons[gActiveBank].maxHP / 4 || gBattleMons[gActiveBank].maxHP - gBattleMons[gActiveBank].hp > itemEffects[paramOffset])
+                shouldUse = TRUE;
+            break;
+        case AI_ITEM_CURE_CONDITION:
+            *(gBattleStruct->AI_itemFlags + gActiveBank / 2) = 0;
+            if (itemEffects[3] & 0x20 && gBattleMons[gActiveBank].status1 & STATUS_SLEEP)
+            {
+                *(gBattleStruct->AI_itemFlags + gActiveBank / 2) |= 0x20;
+                shouldUse = TRUE;
+            }
+            if (itemEffects[3] & 0x10 && (gBattleMons[gActiveBank].status1 & STATUS_POISON || gBattleMons[gActiveBank].status1 & STATUS_TOXIC_POISON))
+            {
+                *(gBattleStruct->AI_itemFlags + gActiveBank / 2) |= 0x10;
+                shouldUse = TRUE;
+            }
+            if (itemEffects[3] & 0x8 && gBattleMons[gActiveBank].status1 & STATUS_BURN)
+            {
+                *(gBattleStruct->AI_itemFlags + gActiveBank / 2) |= 0x8;
+                shouldUse = TRUE;
+            }
+            if (itemEffects[3] & 0x4 && gBattleMons[gActiveBank].status1 & STATUS_FREEZE)
+            {
+                *(gBattleStruct->AI_itemFlags + gActiveBank / 2) |= 0x4;
+                shouldUse = TRUE;
+            }
+            if (itemEffects[3] & 0x2 && gBattleMons[gActiveBank].status1 & STATUS_PARALYSIS)
+            {
+                *(gBattleStruct->AI_itemFlags + gActiveBank / 2) |= 0x2;
+                shouldUse = TRUE;
+            }
+            if (itemEffects[3] & 0x1 && gBattleMons[gActiveBank].status2 & STATUS2_CONFUSION)
+            {
+                *(gBattleStruct->AI_itemFlags + gActiveBank / 2) |= 0x1;
+                shouldUse = TRUE;
+            }
+            break;
+        case AI_ITEM_X_STAT:
+            *(gBattleStruct->AI_itemFlags + gActiveBank / 2) = 0;
+            if (gDisableStructs[gActiveBank].isFirstTurn == 0)
+                break;
+            if (itemEffects[0] & 0xF)
+                *(gBattleStruct->AI_itemFlags + gActiveBank / 2) |= 0x1;
+            if (itemEffects[1] & 0xF0)
+                *(gBattleStruct->AI_itemFlags + gActiveBank / 2) |= 0x2;
+            if (itemEffects[1] & 0xF)
+                *(gBattleStruct->AI_itemFlags + gActiveBank / 2) |= 0x4;
+            if (itemEffects[2] & 0xF)
+                *(gBattleStruct->AI_itemFlags + gActiveBank / 2) |= 0x8;
+            if (itemEffects[2] & 0xF0)
+                *(gBattleStruct->AI_itemFlags + gActiveBank / 2) |= 0x20;
+            if (itemEffects[0] & 0x30)
+                *(gBattleStruct->AI_itemFlags + gActiveBank / 2) |= 0x80;
+            shouldUse = TRUE;
+            break;
+        case AI_ITEM_GUARD_SPECS:
+            bankSide = GetBankSide(gActiveBank);
+            if (gDisableStructs[gActiveBank].isFirstTurn != 0 && gSideTimers[bankSide].mistTimer == 0)
+                shouldUse = TRUE;
+            break;
+        case AI_ITEM_NOT_RECOGNIZABLE:
+            return FALSE;
+        }
+
+        if (shouldUse)
+        {
+            EmitCmd_x21(1, 1, 0);
+            *(gBattleStruct->field_C0 + (gActiveBank / 2) * 2) = item;
+            gBattleResources->battleHistory->trainerItems[i] = 0;
+            return shouldUse;
+        }
+    }
+
+    return FALSE;
+}

src/battle_script_commands.c

@@ -1772,11 +1772,11 @@ u8 TypeCalc(u16 move, u8 bankAtk, u8 bankDef)
     return flags;
 }
 
-u8 AI_TypeCalc(u16 move, u16 species, u8 ability)
+u8 AI_TypeCalc(u16 move, u16 targetSpecies, u8 targetAbility)
 {
     s32 i = 0;
     u8 flags = 0;
-    u8 type1 = gBaseStats[species].type1, type2 = gBaseStats[species].type2;
+    u8 type1 = gBaseStats[targetSpecies].type1, type2 = gBaseStats[targetSpecies].type2;
     u8 moveType;
 
     if (move == MOVE_STRUGGLE)
@@ -1784,7 +1784,7 @@ u8 AI_TypeCalc(u16 move, u16 species, u8 ability)
 
     moveType = gBattleMoves[move].type;
 
-    if (ability == ABILITY_LEVITATE && moveType == TYPE_GROUND)
+    if (targetAbility == ABILITY_LEVITATE && moveType == TYPE_GROUND)
     {
         flags = MOVESTATUS_MISSED | MOVESTATUS_NOTAFFECTED;
     }
@@ -1809,7 +1809,7 @@ u8 AI_TypeCalc(u16 move, u16 species, u8 ability)
             i += 3;
         }
     }
-    if (ability == ABILITY_WONDER_GUARD
+    if (targetAbility == ABILITY_WONDER_GUARD
      && (!(flags & MOVESTATUS_SUPEREFFECTIVE) || ((flags & (MOVESTATUS_SUPEREFFECTIVE | MOVESTATUS_NOTVERYEFFECTIVE)) == (MOVESTATUS_SUPEREFFECTIVE | MOVESTATUS_NOTVERYEFFECTIVE)))
      && gBattleMoves[move].power)
         flags |= MOVESTATUS_NOTAFFECTED;