Start renaming symbols

I finally figured out what the code is trying to do. I have a foothold;
the rest should follow.

include/cable_club.h

@@ -15,6 +15,6 @@ void sub_80B360C(void);
 bool32 sub_80B2AF4(u16 *arg0, u16 *arg1);
 void sub_80B3AF8(u8 taskId);
 void task00_08081A90(u8 taskId);
-bool32 sub_80B39D4(u8 linkPlayerIndex);
+bool32 GetLinkTrainerCardColor(u8 linkPlayerIndex);
 
 #endif //GUARD_CABLE_CLUB_H

include/global.h

@@ -907,12 +907,12 @@ struct MapPosition
     s8 height;
 };
 
-struct UnkStruct_8054FF8
+struct TradeRoomTrainer
 {
     u8 a;
     u8 b;
     u8 c;
-    u8 d;
+    u8 facing;
     struct MapPosition sub;
     u16 field_C;
 };

include/overworld.h

@@ -25,7 +25,7 @@ extern u16 *gBGTilemapBuffers3;
 extern u16 gUnknown_03005DA8;
 extern void (*gFieldCallback)(void);
 extern bool8 (*gFieldCallback2)(void);
-extern u8 gUnknown_03005DB4;
+extern u8 gLinkGuestPlayerId;
 extern u8 gFieldLinkPlayerCount;
 
 // Exported ROM declarations

include/trainer_card.h

@@ -43,7 +43,7 @@ struct TrainerCard
 extern struct TrainerCard gTrainerCards[4];
 
 u32 CountPlayerTrainerStars(void);
-u8 sub_80C4904(u8 cardId);
+u8 GetTrainerCardStars(u8 cardId);
 void CopyTrainerCardData(struct TrainerCard *dst, u16 *src, u8 gameVersion);
 void ShowPlayerTrainerCard(void (*callback)(void));
 void ShowTrainerCardInLink(u8 arg0, void (*callback)(void));