diff --git a/include/battle.h b/include/battle.h
index db406e4b2..7775d5ba2 100644
--- a/include/battle.h
+++ b/include/battle.h
@@ -29,10 +29,10 @@
    (!(gBattleMons[battler].status2 & STATUS2_TRANSFORMED)           \
  && !(gDisableStructs[battler].mimickedMoves & gBitTable[moveSlot]))
 
-#define TRAINER_OPPONENT_3FE        0x3FE
-#define TRAINER_OPPONENT_C00        0xC00
-#define TRAINER_LINK_OPPONENT       0x800
-#define SECRET_BASE_OPPONENT        0x400
+// Special Trainer Ids.
+#define TRAINER_UNION_ROOM          3072
+#define TRAINER_LINK_OPPONENT       2048
+#define TRAINER_SECRET_BASE         1024
 
 // Battle Actions
 // These determine what each battler will do in a turn
diff --git a/src/battle_ai_script_commands.c b/src/battle_ai_script_commands.c
index eaa203a54..3c9ff75f0 100644
--- a/src/battle_ai_script_commands.c
+++ b/src/battle_ai_script_commands.c
@@ -269,7 +269,7 @@ void BattleAI_HandleItemUseBeforeAISetup(void)
 
     // Items are allowed to use in ONLY trainer battles.
     if ((gBattleTypeFlags & BATTLE_TYPE_TRAINER)
-        && (gTrainerBattleOpponent_A != SECRET_BASE_OPPONENT)
+        && (gTrainerBattleOpponent_A != TRAINER_SECRET_BASE)
         && !(gBattleTypeFlags & (BATTLE_TYPE_TRAINER_TOWER | BATTLE_TYPE_EREADER_TRAINER | BATTLE_TYPE_BATTLE_TOWER | BATTLE_TYPE_SAFARI | BATTLE_TYPE_LINK))
         )
     {
@@ -339,7 +339,7 @@ void BattleAI_SetupAIData(void)
         AI_THINKING_STRUCT->aiFlags = AI_SCRIPT_ROAMING;
         return;
     }
-    else if (!(gBattleTypeFlags & (BATTLE_TYPE_TRAINER_TOWER | BATTLE_TYPE_EREADER_TRAINER | BATTLE_TYPE_BATTLE_TOWER)) && (gTrainerBattleOpponent_A != SECRET_BASE_OPPONENT))
+    else if (!(gBattleTypeFlags & (BATTLE_TYPE_TRAINER_TOWER | BATTLE_TYPE_EREADER_TRAINER | BATTLE_TYPE_BATTLE_TOWER)) && (gTrainerBattleOpponent_A != TRAINER_SECRET_BASE))
     {
         if (gBattleTypeFlags & BATTLE_TYPE_WILD_SCRIPTED)
         {
diff --git a/src/battle_controller_link_opponent.c b/src/battle_controller_link_opponent.c
index 54d031e9f..3c570ad57 100644
--- a/src/battle_controller_link_opponent.c
+++ b/src/battle_controller_link_opponent.c
@@ -1135,7 +1135,7 @@ static void LinkOpponentHandleDrawTrainerPic(void)
     else
     {
         xPos = 176;
-        if (gTrainerBattleOpponent_A == TRAINER_OPPONENT_C00)
+        if (gTrainerBattleOpponent_A == TRAINER_UNION_ROOM)
         {
             trainerPicId = GetUnionRoomTrainerPic();
         }
diff --git a/src/battle_controller_opponent.c b/src/battle_controller_opponent.c
index 6e8190985..6913dfbc2 100644
--- a/src/battle_controller_opponent.c
+++ b/src/battle_controller_opponent.c
@@ -1122,7 +1122,7 @@ static void OpponentHandleDrawTrainerPic(void)
 {
     u32 trainerPicId;
 
-    if (gTrainerBattleOpponent_A == 0x400)
+    if (gTrainerBattleOpponent_A == TRAINER_SECRET_BASE)
         trainerPicId = GetSecretBaseTrainerPicIndex();
     else if (gBattleTypeFlags & BATTLE_TYPE_BATTLE_TOWER)
         trainerPicId = GetBattleTowerTrainerFrontSpriteId();
@@ -1152,7 +1152,7 @@ static void OpponentHandleTrainerSlide(void)
 {
     u32 trainerPicId;
 
-    if (gTrainerBattleOpponent_A == 0x400)
+    if (gTrainerBattleOpponent_A == TRAINER_SECRET_BASE)
         trainerPicId = GetSecretBaseTrainerPicIndex();
     else if (gBattleTypeFlags & BATTLE_TYPE_BATTLE_TOWER)
         trainerPicId = GetBattleTowerTrainerFrontSpriteId();
diff --git a/src/battle_message.c b/src/battle_message.c
index a845fe57c..519c03a30 100644
--- a/src/battle_message.c
+++ b/src/battle_message.c
@@ -1499,7 +1499,7 @@ void BufferStringBattle(u16 stringId)
                 }
                 else
                 {
-                    if (gTrainerBattleOpponent_A == TRAINER_OPPONENT_C00)
+                    if (gTrainerBattleOpponent_A == TRAINER_UNION_ROOM)
                         stringPtr = sText_Trainer1WantsToBattle;
                     else
                         stringPtr = sText_LinkTrainerWantsToBattle;
@@ -1559,7 +1559,7 @@ void BufferStringBattle(u16 stringId)
             {
                 if (!(gBattleTypeFlags & BATTLE_TYPE_LINK))
                     stringPtr = sText_Trainer1SentOutPkmn;
-                else if (gTrainerBattleOpponent_A == TRAINER_OPPONENT_C00)
+                else if (gTrainerBattleOpponent_A == TRAINER_UNION_ROOM)
                     stringPtr = sText_Trainer1SentOutPkmn;
                 else
                     stringPtr = sText_LinkTrainerSentOutPkmn;
@@ -1611,7 +1611,7 @@ void BufferStringBattle(u16 stringId)
             {
                 if (gBattleTypeFlags & BATTLE_TYPE_MULTI)
                     stringPtr = sText_LinkTrainerMultiSentOutPkmn;
-                else if (gTrainerBattleOpponent_A == TRAINER_OPPONENT_C00)
+                else if (gTrainerBattleOpponent_A == TRAINER_UNION_ROOM)
                     stringPtr = sText_Trainer1SentOutPkmn2;
                 else
                     stringPtr = sText_LinkTrainerSentOutPkmn2;
@@ -1644,7 +1644,7 @@ void BufferStringBattle(u16 stringId)
                 stringPtr = sText_GotAwaySafely;
             else if (gBattleTypeFlags & BATTLE_TYPE_MULTI)
                 stringPtr = sText_TwoWildFled;
-            else if (gTrainerBattleOpponent_A == TRAINER_OPPONENT_C00)
+            else if (gTrainerBattleOpponent_A == TRAINER_UNION_ROOM)
                 stringPtr = gUnknown_83FE9D4;
             else
                 stringPtr = sText_WildFled;
@@ -1669,7 +1669,7 @@ void BufferStringBattle(u16 stringId)
                     break;
                 }
             }
-            else if (gTrainerBattleOpponent_A == TRAINER_OPPONENT_C00)
+            else if (gTrainerBattleOpponent_A == TRAINER_UNION_ROOM)
             {
                 switch (gBattleTextBuff1[0])
                 {
@@ -1981,9 +1981,9 @@ u32 BattleStringExpandPlaceholders(const u8 *src, u8 *dst)
                 toCpy = gAbilityNames[sBattlerAbilities[gEffectBattler]];
                 break;
             case B_TXT_TRAINER1_CLASS: // trainer class name
-                if (gTrainerBattleOpponent_A == SECRET_BASE_OPPONENT)
+                if (gTrainerBattleOpponent_A == TRAINER_SECRET_BASE)
                     toCpy = gTrainerClassNames[GetSecretBaseTrainerNameIndex()];
-                else if (gTrainerBattleOpponent_A == TRAINER_OPPONENT_C00)
+                else if (gTrainerBattleOpponent_A == TRAINER_UNION_ROOM)
                     toCpy = gTrainerClassNames[GetUnionRoomTrainerClass()];
                 else if (gBattleTypeFlags & BATTLE_TYPE_BATTLE_TOWER)
                     toCpy = gTrainerClassNames[GetBattleTowerTrainerClassNameId()];
@@ -1995,14 +1995,14 @@ u32 BattleStringExpandPlaceholders(const u8 *src, u8 *dst)
                     toCpy = gTrainerClassNames[gTrainers[gTrainerBattleOpponent_A].trainerClass];
                 break;
             case B_TXT_TRAINER1_NAME: // trainer1 name
-                if (gTrainerBattleOpponent_A == SECRET_BASE_OPPONENT)
+                if (gTrainerBattleOpponent_A == TRAINER_SECRET_BASE)
                 {
                     for (i = 0; i < (s32)NELEMS(gBattleResources->secretBase->trainerName); i++)
                         text[i] = gBattleResources->secretBase->trainerName[i];
                     text[i] = EOS;
                     toCpy = text;
                 }
-                if (gTrainerBattleOpponent_A == TRAINER_OPPONENT_C00)
+                if (gTrainerBattleOpponent_A == TRAINER_UNION_ROOM)
                 {
                     toCpy = gLinkPlayers[multiplayerId ^ BIT_SIDE].name;
                 }
diff --git a/src/pokemon.c b/src/pokemon.c
index 066a2a9a0..60a7a8d0d 100644
--- a/src/pokemon.c
+++ b/src/pokemon.c
@@ -3796,7 +3796,7 @@ static void CreateSecretBaseEnemyParty(struct SecretBaseRecord *secretBaseRecord
         }
     }
     gBattleTypeFlags = 8;
-    gTrainerBattleOpponent_A = SECRET_BASE_OPPONENT;
+    gTrainerBattleOpponent_A = TRAINER_SECRET_BASE;
 }
 
 u8 GetSecretBaseTrainerPicIndex(void)
diff --git a/src/union_room_battle.c b/src/union_room_battle.c
index 56676ab7b..907c9ef8d 100644
--- a/src/union_room_battle.c
+++ b/src/union_room_battle.c
@@ -58,7 +58,7 @@ static void SetUpPartiesAndStartBattle(void)
     }
     IncrementGameStat(GAME_STAT_NUM_UNION_ROOM_BATTLES);
     CalculatePlayerPartyCount();
-    gTrainerBattleOpponent_A = TRAINER_OPPONENT_C00;
+    gTrainerBattleOpponent_A = TRAINER_UNION_ROOM;
     SetMainCallback2(CB2_InitBattle);
 }