diff --git a/include/battle/ov16_0223DF00.h b/include/battle/ov16_0223DF00.h
index ad4c3060a3..6249b8cdf0 100644
--- a/include/battle/ov16_0223DF00.h
+++ b/include/battle/ov16_0223DF00.h
@@ -13,7 +13,7 @@
 #include "struct_decls/struct_0200C704_decl.h"
 #include "struct_decls/struct_020797DC_decl.h"
 #include "struct_defs/chatot_cry.h"
-#include "struct_defs/trainer_data.h"
+#include "struct_defs/trainer.h"
 
 #include "battle/battle_context.h"
 #include "battle/battle_message.h"
diff --git a/include/field_battle_data_transfer.h b/include/field_battle_data_transfer.h
index 332d0ba11a..2a35879ab4 100644
--- a/include/field_battle_data_transfer.h
+++ b/include/field_battle_data_transfer.h
@@ -10,7 +10,7 @@
 #include "struct_decls/struct_0206D140_decl.h"
 #include "struct_decls/struct_020797DC_decl.h"
 #include "struct_defs/chatot_cry.h"
-#include "struct_defs/trainer_data.h"
+#include "struct_defs/trainer.h"
 
 #include "field/field_system_decl.h"
 
diff --git a/include/string_template.h b/include/string_template.h
index 55a5697728..fa31bf868e 100644
--- a/include/string_template.h
+++ b/include/string_template.h
@@ -6,7 +6,7 @@
 
 #include "struct_decls/struct_020797DC_decl.h"
 #include "struct_defs/pokemon.h"
-#include "struct_defs/trainer_data.h"
+#include "struct_defs/trainer.h"
 
 #include "enums.h"
 #include "savedata.h"
diff --git a/include/struct_defs/battle_system.h b/include/struct_defs/battle_system.h
index 671e8fb024..81f1d25b0d 100644
--- a/include/struct_defs/battle_system.h
+++ b/include/struct_defs/battle_system.h
@@ -17,7 +17,7 @@
 #include "struct_decls/struct_020797DC_decl.h"
 #include "struct_defs/chatot_cry.h"
 #include "struct_defs/struct_0207C690.h"
-#include "struct_defs/trainer_data.h"
+#include "struct_defs/trainer.h"
 
 #include "battle/battle_context.h"
 #include "battle/struct_ov16_0223E0C8.h"
diff --git a/include/struct_defs/struct_0202FAA8.h b/include/struct_defs/struct_0202FAA8.h
index 1af308b10e..f8004856fd 100644
--- a/include/struct_defs/struct_0202FAA8.h
+++ b/include/struct_defs/struct_0202FAA8.h
@@ -1,7 +1,7 @@
 #ifndef POKEPLATINUM_STRUCT_0202FAA8_H
 #define POKEPLATINUM_STRUCT_0202FAA8_H
 
-#include "struct_defs/trainer_data.h"
+#include "struct_defs/trainer.h"
 
 typedef struct {
     u32 unk_00;
diff --git a/include/struct_defs/trainer.h b/include/struct_defs/trainer.h
new file mode 100644
index 0000000000..e4de20d13a
--- /dev/null
+++ b/include/struct_defs/trainer.h
@@ -0,0 +1,19 @@
+#ifndef POKEPLATINUM_STRUCT_TRAINER_H
+#define POKEPLATINUM_STRUCT_TRAINER_H
+
+#include "constants/string.h"
+
+#include "struct_defs/sentence.h"
+#include "struct_defs/trainer_data.h"
+
+#include "charcode.h"
+
+typedef struct Trainer {
+    TrainerHeader header;
+
+    charcode_t name[TRAINER_NAME_LEN + 1];
+    Sentence winMsg;
+    Sentence loseMsg;
+} Trainer;
+
+#endif // POKEPLATINUM_STRUCT_TRAINER_H
diff --git a/include/struct_defs/trainer_data.h b/include/struct_defs/trainer_data.h
index bc2a7a0e07..e776babe77 100644
--- a/include/struct_defs/trainer_data.h
+++ b/include/struct_defs/trainer_data.h
@@ -1,11 +1,16 @@
 #ifndef POKEPLATINUM_STRUCT_TRAINER_DATA_H
 #define POKEPLATINUM_STRUCT_TRAINER_DATA_H
 
-#include "constants/string.h"
+/*
+ * Note: *most* source files should not include this header directly, and should
+ * instead including `struct_defs/trainer.h`. This header is held separately for
+ * use by data-packing routines.
+ */
 
-#include "struct_defs/sentence.h"
+#include "constants/moves.h"
 
-#include "strbuf.h"
+#define MAX_TRAINER_ITEMS 4
+#define MAX_DV            255
 
 enum TrainerDataType {
     TRDATATYPE_BASE = 0,
@@ -14,71 +19,46 @@ enum TrainerDataType {
     TRDATATYPE_WITH_MOVES_AND_ITEM,
 };
 
-/**
- * @brief Trainer data encapsulation. Contains all trainer-level data needed to instantiate a trainer battle.
- */
-typedef struct Trainer {
-    u8 type; //< The data type of the trainer; controls which TrainerMon struct is used for the party.
-    u8 class; //< The trainer's class, e.g. "Youngster" or "Gym Leader."
-    u8 sprite; //< Which sprite ID the trainer uses.
-    u8 partySize; //< How many Pokemon the trainer has in their party.
+typedef struct TrainerHeader {
+    u8 monDataType;
+    u8 trainerType;
+    u8 sprite;
+    u8 partySize;
+    u16 items[MAX_TRAINER_ITEMS];
+    u32 aiMask;
+    u32 battleType;
+} TrainerHeader;
 
-    u16 items[4]; //< Items that the trainer has in their bag.
-
-    u32 aiMask; //< Mask of AI flags to use for this trainer in battle.
-
-    u32 battleType; //< The type of battle to be instantiated.
-
-    charcode_t name[TRAINER_NAME_LEN + 1]; //< The trainer's name.
-
-    Sentence winMsg; //< The message to display if the trainer wins.
-    Sentence loseMsg; //< The message to display if the trainer loses.
-} Trainer;
-
-#define MAX_DV 255
-
-/**
- * @brief The most basic Trainer Pokemon structure. No item is held, and moves are populated from the learnset.
- */
 typedef struct TrainerMonBase {
-    u16 dv; //< Difficulty value; determines how many IVs the Pokemon will have in each stat.
-    u16 level; //< The Pokemon's level.
-    u16 species; //< Composite mask of the Pokemon's level (least-significant 10 bits) and form (most-significant 6 bits).
-    u16 cbSeal; //< Ball seal applied to the Pokemon.
+    u16 dv;
+    u16 level;
+    u16 species;
+    u16 cbSeal;
 } TrainerMonBase;
 
-/**
- * @brief Trainer Pokemon that knows a certain set of moves.
- */
 typedef struct TrainerMonWithMoves {
-    u16 dv; //< Difficulty value; determines how many IVs the Pokemon will have in each stat.
-    u16 level; //< The Pokemon's level.
-    u16 species; //< Composite mask of the Pokemon's level (least-significant 10 bits) and form (most-significant 6 bits).
-    u16 moves[4]; //< The Pokemon's known moves.
-    u16 cbSeal; //< Ball seal applied to the Pokemon.
+    u16 dv;
+    u16 level;
+    u16 species;
+    u16 moves[LEARNED_MOVES_MAX];
+    u16 cbSeal;
 } TrainerMonWithMoves;
 
-/**
- * @brief Trainer Pokemon that has a specific held item.
- */
 typedef struct TrainerMonWithItem {
-    u16 dv; //< Difficulty value; determines how many IVs the Pokemon will have in each stat.
-    u16 level; //< The Pokemon's level.
-    u16 species; //< Composite mask of the Pokemon's level (least-significant 10 bits) and form (most-significant 6 bits).
-    u16 item; //< The Pokemon's held item.
-    u16 cbSeal; //< Ball seal applied to the Pokemon.
+    u16 dv;
+    u16 level;
+    u16 species;
+    u16 item;
+    u16 cbSeal;
 } TrainerMonWithItem;
 
-/**
- * @brief Trainer Pokemon that has a specific held item and knows a certain set of moves.
- */
 typedef struct TrainerMonWithMovesAndItem {
-    u16 dv; //< Difficulty value; determines how many IVs the Pokemon will have in each stat.
-    u16 level; //< The Pokemon's level.
-    u16 species; //< Composite mask of the Pokemon's level (least-significant 10 bits) and form (most-significant 6 bits).
-    u16 item; //< The Pokemon's held item.
-    u16 moves[4]; //< The Pokemon's known moves.
-    u16 cbSeal; //< Ball seal applied to the Pokemon.
+    u16 dv;
+    u16 level;
+    u16 species;
+    u16 item;
+    u16 moves[LEARNED_MOVES_MAX];
+    u16 cbSeal;
 } TrainerMonWithMovesAndItem;
 
 #endif // POKEPLATINUM_STRUCT_TRAINER_DATA_H
diff --git a/include/trainer_data.h b/include/trainer_data.h
index 4e4a38813d..81dafbbc01 100644
--- a/include/trainer_data.h
+++ b/include/trainer_data.h
@@ -3,7 +3,7 @@
 
 #include "constants/trainer.h"
 
-#include "struct_defs/trainer_data.h"
+#include "struct_defs/trainer.h"
 
 #include "field_battle_data_transfer.h"
 #include "savedata.h"
@@ -78,7 +78,7 @@ void Trainer_Load(int trainerID, Trainer *trdata);
  *
  * The struct pointer passed to this function will determine exactly how much
  * data is loaded; see the definitions of the various TrainerMon... structs in
- * struct_defs/trainer_data.h for exact specifications.
+ * struct_defs/trainer.h for exact specifications.
  *
  * @param trainerID     ID of the trainer whose party is to be loaded.
  * @param[out] trparty  Struct which will contain the loaded trainer party data.
diff --git a/src/battle/battle_controller.c b/src/battle/battle_controller.c
index 2c94b843b0..fa57aff72a 100644
--- a/src/battle/battle_controller.c
+++ b/src/battle/battle_controller.c
@@ -17,7 +17,7 @@
 #include "generated/sdat.h"
 
 #include "struct_decls/battle_system.h"
-#include "struct_defs/trainer_data.h"
+#include "struct_defs/trainer.h"
 
 #include "battle/ai_context.h"
 #include "battle/battle_context.h"
@@ -4268,7 +4268,7 @@ static BOOL BattleController_CheckBattleOver(BattleSystem *battleSys, BattleCont
         || (battleResult == BATTLE_RESULT_WIN && (battleType & BATTLE_TYPE_FRONTIER) && (battleType & BATTLE_TYPE_LINK) == FALSE)) {
         Trainer *trainer = BattleSystem_GetTrainer(battleSys, BATTLER_ENEMY_1);
 
-        switch (trainer->class) {
+        switch (trainer->header.trainerType) {
         case TRAINER_CLASS_LEADER_ROARK:
         case TRAINER_CLASS_LEADER_GARDENIA:
         case TRAINER_CLASS_LEADER_WAKE:
diff --git a/src/battle/battle_display.c b/src/battle/battle_display.c
index 91487f581e..eb10b18a24 100644
--- a/src/battle/battle_display.c
+++ b/src/battle/battle_display.c
@@ -15,7 +15,7 @@
 #include "struct_defs/battle_io.h"
 #include "struct_defs/sprite_animation_frame.h"
 #include "struct_defs/struct_0200D0F4.h"
-#include "struct_defs/trainer_data.h"
+#include "struct_defs/trainer.h"
 
 #include "battle/battle_context.h"
 #include "battle/battle_io.h"
@@ -554,7 +554,7 @@ void ov16_0225D360(BattleSystem *param0, BattlerData *param1, UnkStruct_ov16_022
         {
             Trainer *trainer = BattleSystem_GetTrainer(param0, param1->battler);
             v0->unk_0B = 0;
-            v0->unk_0C = sub_020788D0(ov16_02264768(param0, param1->battler, trainer->class));
+            v0->unk_0C = sub_020788D0(ov16_02264768(param0, param1->battler, trainer->header.trainerType));
         }
     }
 
diff --git a/src/battle/battle_io.c b/src/battle/battle_io.c
index 0f8e9721c2..aba95aad46 100644
--- a/src/battle/battle_io.c
+++ b/src/battle/battle_io.c
@@ -419,7 +419,7 @@ void BattleIO_SetTrainerEncounter(BattleSystem *param0, int param1)
     UnkStruct_ov16_02265124 v0;
 
     v0.unk_00 = 8;
-    v0.unk_02 = param0->trainers[param1].class;
+    v0.unk_02 = param0->trainers[param1].header.trainerType;
     v0.unk_01 = param0->unk_A8[param1];
 
     SendMessage(param0, 1, param1, &v0, sizeof(UnkStruct_ov16_02265124));
@@ -448,7 +448,7 @@ void BattleIO_SlideTrainerIn(BattleSystem *param0, int param1, int param2)
     UnkStruct_ov16_022651A8 v0;
 
     v0.unk_00 = 11;
-    v0.unk_02 = param0->trainers[param1].class;
+    v0.unk_02 = param0->trainers[param1].header.trainerType;
     v0.unk_01 = param0->unk_A8[param1];
     v0.unk_04 = param2;
 
diff --git a/src/battle/battle_script.c b/src/battle/battle_script.c
index eb032b5a7a..c6d35b97da 100644
--- a/src/battle/battle_script.c
+++ b/src/battle/battle_script.c
@@ -26,7 +26,7 @@
 #include "struct_defs/struct_0200D0F4.h"
 #include "struct_defs/struct_020127E8.h"
 #include "struct_defs/struct_0208737C.h"
-#include "struct_defs/trainer_data.h"
+#include "struct_defs/trainer.h"
 
 #include "battle/battle_context.h"
 #include "battle/battle_controller.h"
@@ -3879,40 +3879,40 @@ static u32 BattleScript_CalcPrizeMoney(BattleSystem *battleSys, BattleContext *b
     Trainer_Load(battleSys->trainerIDs[battler], &trainer);
     Trainer_LoadParty(battleSys->trainerIDs[battler], rawParty);
 
-    switch (trainer.type) {
+    switch (trainer.header.monDataType) {
     default:
     case TRDATATYPE_BASE: {
         TrainerMonBase *party = (TrainerMonBase *)rawParty;
-        lastLevel = party[trainer.partySize - 1].level;
+        lastLevel = party[trainer.header.partySize - 1].level;
         break;
     }
 
     case TRDATATYPE_WITH_MOVES: {
         TrainerMonWithMoves *party = (TrainerMonWithMoves *)rawParty;
-        lastLevel = party[trainer.partySize - 1].level;
+        lastLevel = party[trainer.header.partySize - 1].level;
         break;
     }
 
     case TRDATATYPE_WITH_ITEM: {
         TrainerMonWithItem *party = (TrainerMonWithItem *)rawParty;
-        lastLevel = party[trainer.partySize - 1].level;
+        lastLevel = party[trainer.header.partySize - 1].level;
         break;
     }
 
     case TRDATATYPE_WITH_MOVES_AND_ITEM: {
         TrainerMonWithMovesAndItem *party = (TrainerMonWithMovesAndItem *)rawParty;
-        lastLevel = party[trainer.partySize - 1].level;
+        lastLevel = party[trainer.header.partySize - 1].level;
         break;
     }
     }
 
     u32 prize;
     if ((battleSys->battleType & BATTLE_TYPE_TAG) || battleSys->battleType == BATTLE_TYPE_TRAINER_WITH_AI_PARTNER) {
-        prize = lastLevel * 4 * battleCtx->prizeMoneyMul * sTrainerClassPrizeMul[trainer.class];
+        prize = lastLevel * 4 * battleCtx->prizeMoneyMul * sTrainerClassPrizeMul[trainer.header.trainerType];
     } else if (battleSys->battleType & 0x2) {
-        prize = lastLevel * 4 * battleCtx->prizeMoneyMul * 2 * sTrainerClassPrizeMul[trainer.class];
+        prize = lastLevel * 4 * battleCtx->prizeMoneyMul * 2 * sTrainerClassPrizeMul[trainer.header.trainerType];
     } else {
-        prize = lastLevel * 4 * battleCtx->prizeMoneyMul * sTrainerClassPrizeMul[trainer.class];
+        prize = lastLevel * 4 * battleCtx->prizeMoneyMul * sTrainerClassPrizeMul[trainer.header.trainerType];
     }
 
     Heap_FreeToHeap(rawParty);
diff --git a/src/battle/ov16_0223B140.c b/src/battle/ov16_0223B140.c
index f3b0dc180c..9005c32993 100644
--- a/src/battle/ov16_0223B140.c
+++ b/src/battle/ov16_0223B140.c
@@ -1386,7 +1386,7 @@ static void ov16_0223C2C0(BattleSystem *param0, FieldBattleDTO *param1)
     }
 
     if (param0->battleType & 0x1) {
-        if ((ov16_0223CD3C(param0->trainers[1].class) == 1) || (ov16_0223CD3C(param0->trainers[3].class) == 1)) {
+        if ((ov16_0223CD3C(param0->trainers[1].header.trainerType) == 1) || (ov16_0223CD3C(param0->trainers[3].header.trainerType) == 1)) {
             for (v0 = 0; v0 < Party_GetCurrentCount(param0->parties[0]); v0++) {
                 v3 = Party_GetPokemonBySlotIndex(param0->parties[0], v0);
                 Pokemon_UpdateFriendship(v3, 3, param0->unk_2404);
diff --git a/src/battle/ov16_0223DF00.c b/src/battle/ov16_0223DF00.c
index 08a0a05e19..4492d7c436 100644
--- a/src/battle/ov16_0223DF00.c
+++ b/src/battle/ov16_0223DF00.c
@@ -22,7 +22,7 @@
 #include "struct_defs/battle_system.h"
 #include "struct_defs/chatot_cry.h"
 #include "struct_defs/struct_0200D0F4.h"
-#include "struct_defs/trainer_data.h"
+#include "struct_defs/trainer.h"
 
 #include "battle/battle_context.h"
 #include "battle/battle_display.h"
@@ -1550,7 +1550,7 @@ int ov16_0223F6F0(BattleSystem *battleSystem, u16 param1)
 
 u16 BattleSystem_TrainerItems(BattleSystem *battleSystem, int param1, int param2)
 {
-    return battleSystem->trainers[param1].items[param2];
+    return battleSystem->trainers[param1].header.items[param2];
 }
 
 u32 BattleSystem_RecordingStopped(BattleSystem *battleSystem)
diff --git a/src/battle/trainer_ai/trainer_ai.c b/src/battle/trainer_ai/trainer_ai.c
index 33ed3f1763..e60463bb6a 100644
--- a/src/battle/trainer_ai/trainer_ai.c
+++ b/src/battle/trainer_ai/trainer_ai.c
@@ -353,7 +353,7 @@ void TrainerAI_Init(BattleSystem *battleSys, BattleContext *battleCtx, u8 battle
     if (battleSys->battleType & BATTLE_TYPE_ROAMER) {
         AI_CONTEXT.thinkingMask = AI_FLAG_ROAMING_POKEMON;
     } else {
-        AI_CONTEXT.thinkingMask = battleSys->trainers[battler].aiMask;
+        AI_CONTEXT.thinkingMask = battleSys->trainers[battler].header.aiMask;
     }
 
     // force double-battle strategies, if applicable
diff --git a/src/enc_effects.c b/src/enc_effects.c
index 22b4931a0f..73544689ae 100644
--- a/src/enc_effects.c
+++ b/src/enc_effects.c
@@ -126,7 +126,7 @@ static u32 EncEffects_GetEffectPair(const FieldBattleDTO *dto)
     u32 battleType = dto->battleType;
 
     if (battleType & BATTLE_TYPE_TRAINER) {
-        u32 trainerEffect = EncEffects_TrainerClassEffect(dto->trainer[1].class);
+        u32 trainerEffect = EncEffects_TrainerClassEffect(dto->trainer[1].header.trainerType);
 
         if (battleType & BATTLE_TYPE_FRONTIER) {
             if (trainerEffect == ENCEFF_FRONTIER_BRAIN) {
diff --git a/src/field_battle_data_transfer.c b/src/field_battle_data_transfer.c
index c9f36bf295..30fa530e81 100644
--- a/src/field_battle_data_transfer.c
+++ b/src/field_battle_data_transfer.c
@@ -18,7 +18,7 @@
 #include "struct_defs/chatot_cry.h"
 #include "struct_defs/struct_0202610C.h"
 #include "struct_defs/struct_0205EC34.h"
-#include "struct_defs/trainer_data.h"
+#include "struct_defs/trainer.h"
 
 #include "applications/pokemon_summary_screen/main.h"
 #include "field/field_system.h"
@@ -404,7 +404,7 @@ void FieldBattleDTO_InitWithPartyOrder(FieldBattleDTO *dto, const FieldSystem *f
         int unionAppearance = TrainerInfo_Appearance(trainerInfo);
         int unionGender = TrainerInfo_Gender(trainerInfo);
 
-        dto->trainer[BATTLER_PLAYER_1].class = sub_0205CA14(unionGender, unionAppearance, 1);
+        dto->trainer[BATTLER_PLAYER_1].header.trainerType = sub_0205CA14(unionGender, unionAppearance, 1);
         CharCode_Copy(dto->trainer[BATTLER_PLAYER_1].name, TrainerInfo_Name(dto->trainerInfo[BATTLER_PLAYER_1]));
         dto->trainer[BATTLER_PLAYER_2] = dto->trainer[BATTLER_PLAYER_1];
     } else {
@@ -548,7 +548,7 @@ BOOL CheckPlayerDidNotCaptureWildMon(u32 battleResult)
 
 void FieldBattleDTO_CopyPlayerInfoToTrainerData(FieldBattleDTO *dto)
 {
-    dto->trainer[BATTLER_PLAYER_1].class = TrainerInfo_Gender(dto->trainerInfo[BATTLER_PLAYER_1]);
+    dto->trainer[BATTLER_PLAYER_1].header.trainerType = TrainerInfo_Gender(dto->trainerInfo[BATTLER_PLAYER_1]);
     CharCode_Copy(dto->trainer[BATTLER_PLAYER_1].name, TrainerInfo_Name(dto->trainerInfo[BATTLER_PLAYER_1]));
     dto->trainer[BATTLER_PLAYER_2] = dto->trainer[BATTLER_PLAYER_1];
 }
diff --git a/src/overlay010/ov10_0221F800.c b/src/overlay010/ov10_0221F800.c
index f45b2a416c..bf01ba5c97 100644
--- a/src/overlay010/ov10_0221F800.c
+++ b/src/overlay010/ov10_0221F800.c
@@ -2406,7 +2406,7 @@ static void ov10_022227A4(UnkStruct_ov10_0221F800 *param0)
     battleResult = param0->unk_2A - 1;
 
     if (MapHeader_IsUnionRoom(param0->unk_00->mapHeaderID) == 1) {
-        opponentGender1 = TrainerClass_Gender(param0->unk_00->trainer[v6 ^ 1].class);
+        opponentGender1 = TrainerClass_Gender(param0->unk_00->trainer[v6 ^ 1].header.trainerType);
         opponentName1 = Heap_AllocFromHeap(param0->unk_24, sizeof(u16) * (TRAINER_NAME_LEN + 1));
 
         Strbuf_ToChars(param0->unk_14[sub_020362F4(v6 ^ 1)], opponentName1, TRAINER_NAME_LEN + 1);
@@ -2415,7 +2415,7 @@ static void ov10_022227A4(UnkStruct_ov10_0221F800 *param0)
     } else {
         switch (sub_0203895C()) {
         case 1:
-            opponentGender1 = TrainerClass_Gender(param0->unk_00->trainer[v6 ^ 1].class);
+            opponentGender1 = TrainerClass_Gender(param0->unk_00->trainer[v6 ^ 1].header.trainerType);
             opponentName1 = Heap_AllocFromHeap(param0->unk_24, sizeof(u16) * (TRAINER_NAME_LEN + 1));
 
             Strbuf_ToChars(param0->unk_14[sub_020362F4(v6 ^ 1)], opponentName1, TRAINER_NAME_LEN + 1);
@@ -2424,7 +2424,7 @@ static void ov10_022227A4(UnkStruct_ov10_0221F800 *param0)
             Heap_FreeToHeap(opponentName1);
             break;
         case 2:
-            opponentGender1 = TrainerClass_Gender(param0->unk_00->trainer[v6 ^ 1].class);
+            opponentGender1 = TrainerClass_Gender(param0->unk_00->trainer[v6 ^ 1].header.trainerType);
             opponentName1 = Heap_AllocFromHeap(param0->unk_24, sizeof(u16) * (TRAINER_NAME_LEN + 1));
 
             Strbuf_ToChars(param0->unk_14[sub_020362F4(v6 ^ 1)], opponentName1, TRAINER_NAME_LEN + 1);
@@ -2433,7 +2433,7 @@ static void ov10_022227A4(UnkStruct_ov10_0221F800 *param0)
             Heap_FreeToHeap(opponentName1);
             break;
         case 3:
-            opponentGender1 = TrainerClass_Gender(param0->unk_00->trainer[v6 ^ 1].class);
+            opponentGender1 = TrainerClass_Gender(param0->unk_00->trainer[v6 ^ 1].header.trainerType);
             opponentName1 = Heap_AllocFromHeap(param0->unk_24, sizeof(u16) * (TRAINER_NAME_LEN + 1));
 
             Strbuf_ToChars(param0->unk_14[sub_020362F4(v6 ^ 1)], opponentName1, TRAINER_NAME_LEN + 1);
@@ -2446,14 +2446,14 @@ static void ov10_022227A4(UnkStruct_ov10_0221F800 *param0)
             opponentName2 = Heap_AllocFromHeap(param0->unk_24, sizeof(u16) * (TRAINER_NAME_LEN + 1));
 
             if (ov10_02220AD0() == 1) {
-                opponentGender1 = TrainerClass_Gender(param0->unk_00->trainer[1].class);
-                opponentGender2 = TrainerClass_Gender(param0->unk_00->trainer[3].class);
+                opponentGender1 = TrainerClass_Gender(param0->unk_00->trainer[1].header.trainerType);
+                opponentGender2 = TrainerClass_Gender(param0->unk_00->trainer[3].header.trainerType);
 
                 Strbuf_ToChars(param0->unk_14[1], opponentName1, TRAINER_NAME_LEN + 1);
                 Strbuf_ToChars(param0->unk_14[3], opponentName2, TRAINER_NAME_LEN + 1);
             } else {
-                opponentGender1 = TrainerClass_Gender(param0->unk_00->trainer[0].class);
-                opponentGender2 = TrainerClass_Gender(param0->unk_00->trainer[2].class);
+                opponentGender1 = TrainerClass_Gender(param0->unk_00->trainer[0].header.trainerType);
+                opponentGender2 = TrainerClass_Gender(param0->unk_00->trainer[2].header.trainerType);
 
                 Strbuf_ToChars(param0->unk_14[0], opponentName1, TRAINER_NAME_LEN + 1);
                 Strbuf_ToChars(param0->unk_14[2], opponentName2, TRAINER_NAME_LEN + 1);
diff --git a/src/overlay104/ov104_0222DCE0.c b/src/overlay104/ov104_0222DCE0.c
index 439cd72b66..0cfe1ab0f6 100644
--- a/src/overlay104/ov104_0222DCE0.c
+++ b/src/overlay104/ov104_0222DCE0.c
@@ -445,7 +445,7 @@ void ov104_0222E284(FieldBattleDTO *param0, UnkStruct_ov104_0223A348_sub1 *param
     Pokemon *v1;
 
     param0->trainerIDs[param3] = param1->unk_00;
-    param0->trainer[param3].class = param1->unk_04;
+    param0->trainer[param3].header.trainerType = param1->unk_04;
 
     CharCode_Copy(&param0->trainer[param3].name[0], &param1->unk_08[0]);
 
diff --git a/src/overlay104/ov104_0223A0C4.c b/src/overlay104/ov104_0223A0C4.c
index f0c8e8c39a..3fe6bb696f 100644
--- a/src/overlay104/ov104_0223A0C4.c
+++ b/src/overlay104/ov104_0223A0C4.c
@@ -944,7 +944,7 @@ FieldBattleDTO *ov104_0223A580(UnkStruct_0204AFC4 *param0, UnkStruct_ov104_02230
     ov104_0223A6AC(v3, &(param0->unk_78[0]), param0->unk_0E, 1, param0->unk_04);
 
     for (v0 = 0; v0 < 4; v0++) {
-        v3->trainer[v0].aiMask = (0x1 | 0x2 | 0x4);
+        v3->trainer[v0].header.aiMask = (0x1 | 0x2 | 0x4);
     }
 
     switch (param0->unk_0F) {
diff --git a/src/overlay104/ov104_0223A7F4.c b/src/overlay104/ov104_0223A7F4.c
index 090b08dc61..74113849f1 100644
--- a/src/overlay104/ov104_0223A7F4.c
+++ b/src/overlay104/ov104_0223A7F4.c
@@ -381,7 +381,7 @@ FieldBattleDTO *ov104_0223ABA0(UnkStruct_ov104_0223ADA0 *param0, UnkStruct_ov104
     Party_InitWithCapacity(v4->parties[1], ov104_0223AA74(param0->unk_04, 0));
 
     for (v0 = 0; v0 < 4; v0++) {
-        v4->trainer[v0].aiMask = ov104_0223AEE4(param0);
+        v4->trainer[v0].header.aiMask = ov104_0223AEE4(param0);
     }
 
     v5 = Pokemon_New(11);
diff --git a/src/overlay104/ov104_0223AF58.c b/src/overlay104/ov104_0223AF58.c
index e48534399d..8456f8f39b 100644
--- a/src/overlay104/ov104_0223AF58.c
+++ b/src/overlay104/ov104_0223AF58.c
@@ -1619,7 +1619,7 @@ FieldBattleDTO *ov104_0223B250(UnkStruct_ov104_0223B5C0 *param0, UnkStruct_ov104
     v2 = ov104_0223B604(param0, v6, v7);
 
     for (v1 = 0; v1 < 4; v1++) {
-        v8->trainer[v1].aiMask = v2;
+        v8->trainer[v1].header.aiMask = v2;
     }
 
     ov104_0223B518(&param0->unk_290[v6], v7, param0->unk_18[v6], &param0->unk_268[v6], v5, 11, 180);
diff --git a/src/overlay104/ov104_0223B6F4.c b/src/overlay104/ov104_0223B6F4.c
index 4e877946e0..5c2f09c695 100644
--- a/src/overlay104/ov104_0223B6F4.c
+++ b/src/overlay104/ov104_0223B6F4.c
@@ -203,7 +203,7 @@ FieldBattleDTO *ov104_0223B810(UnkStruct_ov104_0223BA10 *param0, UnkStruct_ov104
     Party_InitWithCapacity(v5->parties[1], ov104_0223B7DC(param0->unk_10, 0));
 
     for (v0 = 0; v0 < 4; v0++) {
-        v5->trainer[v0].aiMask = ov104_0223BB10(param0);
+        v5->trainer[v0].header.aiMask = ov104_0223BB10(param0);
     }
 
     v6 = Pokemon_New(11);
diff --git a/src/overlay104/ov104_0223BCBC.c b/src/overlay104/ov104_0223BCBC.c
index 7315b09d66..e1226e0cd4 100644
--- a/src/overlay104/ov104_0223BCBC.c
+++ b/src/overlay104/ov104_0223BCBC.c
@@ -216,7 +216,7 @@ FieldBattleDTO *ov104_0223BDD8(UnkStruct_ov104_0223BFFC *param0, UnkStruct_ov104
     Party_InitWithCapacity(v5->parties[1], ov104_0223BDA4(param0->unk_10, 0));
 
     for (v0 = 0; v0 < 4; v0++) {
-        v5->trainer[v0].aiMask = ov104_0223C0D0(param0);
+        v5->trainer[v0].header.aiMask = ov104_0223C0D0(param0);
     }
 
     v6 = Pokemon_New(11);
diff --git a/src/string_template.c b/src/string_template.c
index 28a462ca1a..748a8f8ea8 100644
--- a/src/string_template.c
+++ b/src/string_template.c
@@ -13,7 +13,7 @@
 #include "generated/text_banks.h"
 
 #include "struct_decls/struct_020797DC_decl.h"
-#include "struct_defs/trainer_data.h"
+#include "struct_defs/trainer.h"
 
 #include "charcode.h"
 #include "enums.h"
@@ -323,7 +323,7 @@ void StringTemplate_SetTrainerClassNameBattle(StringTemplate *template, u32 idx,
     MessageLoader *loader = InitMessageLoader(TEXT_BANK_TRAINER_CLASS_NAMES, template->heapID);
 
     if (loader) {
-        MessageLoader_GetStrbuf(loader, trainer->class, template->templateBuf);
+        MessageLoader_GetStrbuf(loader, trainer->header.trainerType, template->templateBuf);
         SetStringTemplateArg(template, idx, template->templateBuf, NULL);
         MessageLoader_Free(loader);
     }
diff --git a/src/trainer_data.c b/src/trainer_data.c
index 1f3f8bda3b..60542ce83b 100644
--- a/src/trainer_data.c
+++ b/src/trainer_data.c
@@ -1,12 +1,11 @@
-#include "struct_defs/trainer_data.h"
-
-#include <nitro.h>
-#include <string.h>
+#include "trainer_data.h"
 
 #include "constants/battle.h"
 #include "constants/pokemon.h"
 #include "constants/trainer.h"
 
+#include "struct_defs/trainer.h"
+
 #include "data/trainer_class_genders.h"
 
 #include "charcode_util.h"
@@ -20,7 +19,6 @@
 #include "savedata.h"
 #include "savedata_misc.h"
 #include "strbuf.h"
-#include "trainer_data.h"
 
 static void TrainerData_BuildParty(FieldBattleDTO *dto, int battler, int heapID);
 
@@ -38,7 +36,7 @@ void Trainer_Encounter(FieldBattleDTO *dto, const SaveData *save, int heapID)
         Trainer_Load(dto->trainerIDs[i], &trdata);
         dto->trainer[i] = trdata;
 
-        if (trdata.class == TRAINER_CLASS_RIVAL) {
+        if (trdata.header.trainerType == TRAINER_CLASS_RIVAL) {
             CharCode_Copy(dto->trainer[i].name, rivalName);
         } else {
             Strbuf *trainerName = MessageLoader_GetNewStrbuf(msgLoader, dto->trainerIDs[i]);
@@ -49,12 +47,13 @@ void Trainer_Encounter(FieldBattleDTO *dto, const SaveData *save, int heapID)
         TrainerData_BuildParty(dto, i, heapID);
     }
 
-    dto->battleType |= trdata.battleType;
+    dto->battleType |= trdata.header.battleType;
     MessageLoader_Free(msgLoader);
 }
 
 u32 Trainer_LoadParam(int trainerID, enum TrainerDataParam paramID)
 {
+    // TODO: can this be trainerheader?
     u32 result;
     Trainer trdata;
 
@@ -62,34 +61,34 @@ u32 Trainer_LoadParam(int trainerID, enum TrainerDataParam paramID)
 
     switch (paramID) {
     case TRDATA_TYPE:
-        result = trdata.type;
+        result = trdata.header.monDataType;
         break;
 
     case TRDATA_CLASS:
-        result = trdata.class;
+        result = trdata.header.trainerType;
         break;
 
     case TRDATA_SPRITE:
-        result = trdata.sprite;
+        result = trdata.header.sprite;
         break;
 
     case TRDATA_PARTY_SIZE:
-        result = trdata.partySize;
+        result = trdata.header.partySize;
         break;
 
     case TRDATA_ITEM_1:
     case TRDATA_ITEM_2:
     case TRDATA_ITEM_3:
     case TRDATA_ITEM_4:
-        result = trdata.items[paramID - TRDATA_ITEM_1];
+        result = trdata.header.items[paramID - TRDATA_ITEM_1];
         break;
 
     case TRDATA_AI_MASK:
-        result = trdata.aiMask;
+        result = trdata.header.aiMask;
         break;
 
     case TRDATA_BATTLE_TYPE:
-        result = trdata.battleType;
+        result = trdata.header.battleType;
         break;
     }
 
@@ -193,21 +192,21 @@ static void TrainerData_BuildParty(FieldBattleDTO *dto, int battler, int heapID)
     Trainer_LoadParty(dto->trainerIDs[battler], buf);
 
     // determine which magic gender-specific modifier to use for the RNG function
-    genderMod = TrainerClass_Gender(dto->trainer[battler].class) == GENDER_FEMALE
+    genderMod = TrainerClass_Gender(dto->trainer[battler].header.trainerType) == GENDER_FEMALE
         ? 120
         : 136;
 
-    switch (dto->trainer[battler].type) {
+    switch (dto->trainer[battler].header.monDataType) {
     case TRDATATYPE_BASE: {
         TrainerMonBase *trmon = (TrainerMonBase *)buf;
-        for (i = 0; i < dto->trainer[battler].partySize; i++) {
+        for (i = 0; i < dto->trainer[battler].header.partySize; i++) {
             u16 species = trmon[i].species & 0x3FF;
             u8 form = (trmon[i].species & 0xFC00) >> 10;
 
             rnd = trmon[i].dv + trmon[i].level + species + dto->trainerIDs[battler];
             LCRNG_SetSeed(rnd);
 
-            for (j = 0; j < dto->trainer[battler].class; j++) {
+            for (j = 0; j < dto->trainer[battler].header.trainerType; j++) {
                 rnd = LCRNG_Next();
             }
 
@@ -225,14 +224,14 @@ static void TrainerData_BuildParty(FieldBattleDTO *dto, int battler, int heapID)
 
     case TRDATATYPE_WITH_MOVES: {
         TrainerMonWithMoves *trmon = (TrainerMonWithMoves *)buf;
-        for (i = 0; i < dto->trainer[battler].partySize; i++) {
+        for (i = 0; i < dto->trainer[battler].header.partySize; i++) {
             u16 species = trmon[i].species & 0x3FF;
             u8 form = (trmon[i].species & 0xFC00) >> 10;
 
             rnd = trmon[i].dv + trmon[i].level + species + dto->trainerIDs[battler];
             LCRNG_SetSeed(rnd);
 
-            for (j = 0; j < dto->trainer[battler].class; j++) {
+            for (j = 0; j < dto->trainer[battler].header.trainerType; j++) {
                 rnd = LCRNG_Next();
             }
 
@@ -255,14 +254,14 @@ static void TrainerData_BuildParty(FieldBattleDTO *dto, int battler, int heapID)
 
     case TRDATATYPE_WITH_ITEM: {
         TrainerMonWithItem *trmon = (TrainerMonWithItem *)buf;
-        for (i = 0; i < dto->trainer[battler].partySize; i++) {
+        for (i = 0; i < dto->trainer[battler].header.partySize; i++) {
             u16 species = trmon[i].species & 0x3FF;
             u8 form = (trmon[i].species & 0xFC00) >> 10;
 
             rnd = trmon[i].dv + trmon[i].level + species + dto->trainerIDs[battler];
             LCRNG_SetSeed(rnd);
 
-            for (j = 0; j < dto->trainer[battler].class; j++) {
+            for (j = 0; j < dto->trainer[battler].header.trainerType; j++) {
                 rnd = LCRNG_Next();
             }
 
@@ -281,14 +280,14 @@ static void TrainerData_BuildParty(FieldBattleDTO *dto, int battler, int heapID)
 
     case TRDATATYPE_WITH_MOVES_AND_ITEM: {
         TrainerMonWithMovesAndItem *trmon = (TrainerMonWithMovesAndItem *)buf;
-        for (i = 0; i < dto->trainer[battler].partySize; i++) {
+        for (i = 0; i < dto->trainer[battler].header.partySize; i++) {
             u16 species = trmon[i].species & 0x3FF;
             u8 form = (trmon[i].species & 0xFC00) >> 10;
 
             rnd = trmon[i].dv + trmon[i].level + species + dto->trainerIDs[battler];
             LCRNG_SetSeed(rnd);
 
-            for (j = 0; j < dto->trainer[battler].class; j++) {
+            for (j = 0; j < dto->trainer[battler].header.trainerType; j++) {
                 rnd = LCRNG_Next();
             }
 
diff --git a/src/unk_0207A6DC.c b/src/unk_0207A6DC.c
index e17a2dd9bd..3f51753738 100644
--- a/src/unk_0207A6DC.c
+++ b/src/unk_0207A6DC.c
@@ -13,7 +13,7 @@
 #include "struct_defs/struct_0207A81C.h"
 #include "struct_defs/struct_0207ACB4.h"
 #include "struct_defs/struct_0207AD40.h"
-#include "struct_defs/trainer_data.h"
+#include "struct_defs/trainer.h"
 
 #include "battle/battle_io.h"
 #include "battle/ov16_0223DF00.h"
diff --git a/src/unk_0208BA78.c b/src/unk_0208BA78.c
index 4992b2f4d7..df20d26db1 100644
--- a/src/unk_0208BA78.c
+++ b/src/unk_0208BA78.c
@@ -288,7 +288,7 @@ static BOOL sub_0208BC8C(UnkStruct_0208BC3C *param0, int param1)
         sub_0200544C(1, 127);
         sub_02005464(1);
 
-        if (sub_0208BE80(param0->unk_10->trainer[1].class) == 1) {
+        if (sub_0208BE80(param0->unk_10->trainer[1].header.trainerType) == 1) {
             sub_02004550(5, 1202, 1);
         } else {
             sub_02004550(5, 1119, 1);