diff --git a/include/agb_flash.h b/include/agb_flash.h
index 3dd60df0f1..ba5820f016 100644
--- a/include/agb_flash.h
+++ b/include/agb_flash.h
@@ -9,5 +9,6 @@
 
 u16 SetFlashTimerIntr(u8 timerNum, void (**intrFunc)(void));
 u16 IdentifyFlash(void);
+u32 ProgramFlashSectorAndVerify(u16 sectorNum, u8 *src);
 
 #endif //GUARD_AGB_FLASH_H
diff --git a/include/battle_anim.h b/include/battle_anim.h
index 4e241686fd..ac47cadf14 100644
--- a/include/battle_anim.h
+++ b/include/battle_anim.h
@@ -221,6 +221,7 @@ void sub_8117854(u8 taskId, int unused, u16 arg2, u8 battler1, u8 arg4, u8 arg5,
 
 // battle_anim_effects_1.c
 void sub_810310C(u8 battler, struct Sprite* sprite);
+void AnimMoveTwisterParticle(struct Sprite* sprite);
 
 // smokescreen.c
 u8 sub_807521C(s16 x, s16 y, u8 a3);
diff --git a/include/dewford_trend.h b/include/dewford_trend.h
index 608a925f57..bdb0fc95cf 100644
--- a/include/dewford_trend.h
+++ b/include/dewford_trend.h
@@ -5,5 +5,7 @@ void InitDewfordTrend(void);
 void UpdateDewfordTrendPerDay(u16);
 void UpdateDewfordTrendPerDay(u16 days);
 bool8 sub_81226D8(u16 *a);
+void ReceiveEasyChatPairsData(struct EasyChatPair *a, size_t b, u8 unused);
+
 
 #endif // GUARD_DEWFORDTREND_H
diff --git a/include/match_call.h b/include/match_call.h
index 1bf654937d..6803d2f260 100644
--- a/include/match_call.h
+++ b/include/match_call.h
@@ -15,5 +15,6 @@ void InitMatchCallCounters(void);
 bool32 TryStartMatchCall(void);
 bool32 IsMatchCallTaskActive(void);
 void StartMatchCallFromScript(u8* script);
+void sub_8197080(u8 *destStr);
 
 #endif //GUARD_MATCH_CALL_H
diff --git a/include/pokedex.h b/include/pokedex.h
index c3700c8112..a1b7378bfc 100644
--- a/include/pokedex.h
+++ b/include/pokedex.h
@@ -44,5 +44,6 @@ u16 CreateMonSpriteFromNationalDexNumber(u16, s16, s16, u16);
 bool16 HasAllHoennMons(void);
 void ResetPokedexScrollPositions(void);
 u16 sub_80C0944(void);
+void CB2_Pokedex(void);
 
 #endif // GUARD_POKEDEX_H
diff --git a/include/pokemon_icon.h b/include/pokemon_icon.h
index 4f27ef2811..c7b895028c 100644
--- a/include/pokemon_icon.h
+++ b/include/pokemon_icon.h
@@ -23,5 +23,6 @@ void LoadMonIconPalette(u16 species);
 void sub_80D328C(struct Sprite *sprite);
 void sub_80D3014(struct Sprite *sprite);
 void sub_80D32C8(struct Sprite *sprite, u8 animNum);
+u8 sub_80D30A0(u16 species);
 
 #endif // GUARD_POKEMON_ICON_H
diff --git a/include/pokenav.h b/include/pokenav.h
index e5dba8ae09..29ccaec3e5 100644
--- a/include/pokenav.h
+++ b/include/pokenav.h
@@ -30,5 +30,6 @@ u32 sub_81D427C(void);
 void sub_81D4998(void);
 void sub_81D3640(u16 arg0, void* statStoreLocation1, void* statStoreLocation2, u8 arg3, u8 arg4, u8 arg5);
 void sub_81D3784(u16 arg0, void* statStoreLocation1, u8 arg2, u8 arg3, u8 arg4);
+void CB2_InitPokeNav(void);
 
 #endif //GUARD_POKENAV_H
diff --git a/include/rom_8011DC0.h b/include/rom_8011DC0.h
index 9940a5b441..ac9bbb5c30 100644
--- a/include/rom_8011DC0.h
+++ b/include/rom_8011DC0.h
@@ -18,5 +18,6 @@ void sub_801B990(u32, u32);
 u8 sub_8013F78(void);
 bool32 sub_802C908(u16);
 void nullsub_89(u8 taskId);
+void var_800D_set_xB(void);
 
 #endif //GUARD_rom_8011DC0_H
diff --git a/include/save.h b/include/save.h
index 7ce86de705..88e5f22806 100644
--- a/include/save.h
+++ b/include/save.h
@@ -92,4 +92,7 @@ u32 TryCopySpecialSaveSection(u8 sector, u8* dst);
 u32 sub_8153634(u8 sector, u8* src);
 void sub_8153688(u8 taskId);
 
+// save_failed_screen.c
+void DoSaveFailedScreen(u8 saveType);
+
 #endif // GUARD_SAVE_H
diff --git a/include/script.h b/include/script.h
index 386b388d02..34f4635bb3 100644
--- a/include/script.h
+++ b/include/script.h
@@ -61,4 +61,7 @@ bool32 sub_80991F8(void);
 u8 *sub_8099244(void);
 void sub_80992A0(u8 *script, u16 scriptSize);
 
+// srccmd.h
+void sub_809BE48(u16 npcId);
+
 #endif // GUARD_SCRIPT_H
diff --git a/include/secret_base.h b/include/secret_base.h
index 699158d0e6..17efc314d3 100644
--- a/include/secret_base.h
+++ b/include/secret_base.h
@@ -33,6 +33,8 @@ void sub_80E8B6C(void);
 void sub_80E8BC8(void);
 void sub_80E8D4C(void);
 void EnableBothScriptContexts(void);
+void ReceiveSecretBasesData(void *records, size_t recordSize, u8 linkIdx);
+
 
 
 #endif //GUARD_SECRET_BASE_H
diff --git a/include/text.h b/include/text.h
index 96c5a45071..d8f2fd8a35 100644
--- a/include/text.h
+++ b/include/text.h
@@ -284,4 +284,8 @@ void DecompressGlyphFont1(u16 glyphId, bool32 isJapanese);
 u32 GetGlyphWidthFont1(u16 glyphId, bool32 isJapanese);
 void DecompressGlyphFont9(u16 glyphId);
 
+// unk_text_util_2.c
+u16 Font6Func(struct TextPrinter *textPrinter);
+u32 GetGlyphWidthFont6(u16 glyphId, bool32 isJapanese);
+
 #endif // GUARD_TEXT_H
diff --git a/src/dewford_trend.c b/src/dewford_trend.c
index cad5ef9c2a..ee310af04a 100644
--- a/src/dewford_trend.c
+++ b/src/dewford_trend.c
@@ -159,7 +159,7 @@ static void sub_8122804(struct EasyChatPair *s, u16 b, u8 c)
     }
 }
 
-void ReceiveEasyChatPairsData(void *a, u32 b, u8 unused)
+void ReceiveEasyChatPairsData(struct EasyChatPair *a, size_t size, u8 unused)
 {
     u16 i, j, r3, players;
     struct EasyChatPair *buffer1, *buffer2, *src, *dst, *foo_of_buffer2;
@@ -176,7 +176,7 @@ void ReceiveEasyChatPairsData(void *a, u32 b, u8 unused)
         {
             players = GetLinkPlayerCount();
             for (i = 0; i < players; i++)
-                memcpy(&(buffer1[i * 5]), (u8 *)a + i * b, 40);
+                memcpy(&(buffer1[i * 5]), (u8 *)a + i * size, 40);
             src = buffer1;
             dst = buffer2;
             r3 = 0;
diff --git a/src/pokenav.c b/src/pokenav.c
index 41434606cb..62ec75842b 100644
--- a/src/pokenav.c
+++ b/src/pokenav.c
@@ -141,7 +141,7 @@ void sub_81C7710(void);
 static void InitKeys_(void);
 static void FreeVars(void);
 static void VblankCb_Pokenav(void);
-static void Cb2_Pokenav(void);
+static void CB2_Pokenav(void);
 void sub_81C7C28(void);
 void sub_81C72BC(void);
 void sub_81C7B74(void);
@@ -485,7 +485,7 @@ void sub_81C71E4(u8 taskId)
     }
 }
 
-void CB2_PokeNav(void)
+void CB2_InitPokeNav(void)
 {
     gUnknown_0203CF40 = Alloc(sizeof(*gUnknown_0203CF40));
     if (gUnknown_0203CF40 == NULL)
@@ -498,7 +498,7 @@ void CB2_PokeNav(void)
         ResetTasks();
         SetVBlankCallback(NULL);
         CreateTask(sub_81C742C, 0);
-        SetMainCallback2(Cb2_Pokenav);
+        SetMainCallback2(CB2_Pokenav);
         SetVBlankCallback(VblankCb_Pokenav);
     }
 }
@@ -529,7 +529,7 @@ void sub_81C72BC(void)
         FreeAllSpritePalettes();
         SetVBlankCallback(NULL);
         CreateTask(sub_81C742C, 0);
-        SetMainCallback2(Cb2_Pokenav);
+        SetMainCallback2(CB2_Pokenav);
         SetVBlankCallback(VblankCb_Pokenav);
     }
 }
@@ -588,7 +588,7 @@ static bool32 AnyMonHasRibbon(void)
     return FALSE;
 }
 
-static void Cb2_Pokenav(void)
+static void CB2_Pokenav(void)
 {
     RunTasks();
     AnimateSprites();
diff --git a/src/pokenav_match_call.c b/src/pokenav_match_call.c
index 53f9f05484..b775ed10e3 100644
--- a/src/pokenav_match_call.c
+++ b/src/pokenav_match_call.c
@@ -1,13 +1,11 @@
-
-// Includes
 #include "global.h"
 #include "battle_setup.h"
 #include "event_data.h"
 #include "string_util.h"
 #include "battle.h"
 #include "gym_leader_rematch.h"
+#include "match_call.h"
 
-extern void sub_8197080(u8 *dest);
 extern const u8 gTrainerClassNames[][13];
 
 // Static type declarations
diff --git a/src/record_mixing.c b/src/record_mixing.c
index aafd7284ba..ce9bacf4cd 100644
--- a/src/record_mixing.c
+++ b/src/record_mixing.c
@@ -34,9 +34,8 @@
 #include "daycare.h"
 #include "international_string_util.h"
 #include "constants/battle_frontier.h"
+#include "dewford_trend.h"
 
-extern void ReceiveSecretBasesData(struct SecretBaseRecord *, size_t, u8);
-extern void ReceiveEasyChatPairsData(struct EasyChatPair *, size_t, u8);
 
 // Static type declarations
 
diff --git a/src/reshow_battle_screen.c b/src/reshow_battle_screen.c
index 0926d4569e..dd177f8842 100644
--- a/src/reshow_battle_screen.c
+++ b/src/reshow_battle_screen.c
@@ -2,6 +2,7 @@
 #include "reshow_battle_screen.h"
 #include "battle.h"
 #include "palette.h"
+#include "pokemon.h"
 #include "main.h"
 #include "scanline_effect.h"
 #include "text.h"
@@ -18,8 +19,6 @@
 
 extern const union AnimCmd * const * const gMonAnimationsSpriteAnimsPtrTable[];
 
-extern void SetMultiuseSpriteTemplateToTrainerBack(u16 backPicId, u8 battlerPosition);
-
 // this file's functions
 static void CB2_ReshowBattleScreenAfterMenu(void);
 static bool8 LoadBattlerSpriteGfx(u8 battlerId);
diff --git a/src/rock.c b/src/rock.c
index 14ffc63e01..814b1d88bf 100644
--- a/src/rock.c
+++ b/src/rock.c
@@ -12,8 +12,6 @@
 extern const union AnimCmd *const gUnknown_085950E0[];
 extern const union AnimCmd *const gUnknown_085954D0[];
 
-extern void AnimMoveTwisterParticle(struct Sprite *);
-
 void sub_81109F0(struct Sprite *);
 void sub_8110AB4(struct Sprite *);
 void AnimDirtParticleAcrossScreen(struct Sprite *);
diff --git a/src/rom_8011DC0.c b/src/rom_8011DC0.c
index 27472b6e38..b0e861fac3 100644
--- a/src/rom_8011DC0.c
+++ b/src/rom_8011DC0.c
@@ -33,8 +33,7 @@
 #include "start_menu.h"
 #include "data2.h"
 #include "field_screen_effect.h"
-
-extern void HealPlayerParty(void);
+#include "script_pokemon_util_80F87D8.h"
 
 struct UnkStruct_Shared
 {
diff --git a/src/save.c b/src/save.c
index d07e597661..ff26ce4606 100644
--- a/src/save.c
+++ b/src/save.c
@@ -1,5 +1,7 @@
 #include "global.h"
+#include "agb_flash.h"
 #include "gba/flash_internal.h"
+#include "fieldmap.h"
 #include "save.h"
 #include "task.h"
 #include "decompress.h"
@@ -8,6 +10,7 @@
 #include "pokemon_storage_system.h"
 #include "main.h"
 #include "trainer_hill.h"
+#include "link.h"
 #include "constants/game_stat.h"
 
 static u16 CalculateChecksum(void *data, u16 size);
@@ -70,12 +73,6 @@ const struct SaveSectionOffsets gSaveSectionOffsets[] =
     SAVEBLOCK_CHUNK(gPokemonStorage, 8),
 };
 
-extern void DoSaveFailedScreen(u8); // save_failed_screen
-extern bool32 ProgramFlashSectorAndVerify(u8 sector, u8 *data);
-extern void save_serialize_map(void);
-extern void sub_800ADF8(void);
-extern bool8 IsLinkTaskFinished(void);
-
 // iwram common
 u16 gLastWrittenSector;
 u32 gLastSaveCounter;
diff --git a/src/secret_base.c b/src/secret_base.c
index 3e591eba2c..8bb216452d 100644
--- a/src/secret_base.c
+++ b/src/secret_base.c
@@ -43,8 +43,6 @@
 #include "constants/species.h"
 #include "constants/trainers.h"
 
-extern void mapldr_default(void);
-
 // Static type declarations
 
 struct SecretBaseListMenuBuffer {
diff --git a/src/start_menu.c b/src/start_menu.c
index 79404d0b2d..1052b640c2 100644
--- a/src/start_menu.c
+++ b/src/start_menu.c
@@ -7,10 +7,12 @@
 #include "event_object_movement.h"
 #include "event_obj_lock.h"
 #include "event_scripts.h"
+#include "fieldmap.h"
 #include "field_effect.h"
 #include "field_player_avatar.h"
 #include "field_specials.h"
 #include "field_weather.h"
+#include "field_screen_effect.h"
 #include "frontier_pass.h"
 #include "frontier_util.h"
 #include "gpu_regs.h"
@@ -26,6 +28,7 @@
 #include "palette.h"
 #include "party_menu.h"
 #include "pokedex.h"
+#include "pokenav.h"
 #include "safari_zone.h"
 #include "save.h"
 #include "scanline_effect.h"
@@ -40,6 +43,7 @@
 #include "trainer_card.h"
 #include "window.h"
 #include "constants/songs.h"
+#include "rom_8011DC0.h"
 
 // Menu actions
 enum
@@ -84,18 +88,6 @@ EWRAM_DATA static u8 sSaveDialogTimer = 0;
 EWRAM_DATA static bool8 sSavingComplete = FALSE;
 EWRAM_DATA static u8 sSaveInfoWindowId = 0;
 
-// Extern variables.
-extern u8 gLocalLinkPlayerId;
-
-// Extern functions in not decompiled files.
-extern void sub_80AF688(void);
-extern void var_800D_set_xB(void);
-extern void sub_808B864(void);
-extern void CB2_Pokedex(void);
-extern void PlayRainStoppingSoundEffect(void);
-extern void CB2_PokeNav(void);
-extern void save_serialize_map(void);
-
 // Menu action callbacks
 static bool8 StartMenuPokedexCallback(void);
 static bool8 StartMenuPokemonCallback(void);
@@ -656,7 +648,7 @@ static bool8 StartMenuPokeNavCallback(void)
         PlayRainStoppingSoundEffect();
         RemoveExtraStartMenuWindows();
         CleanupOverworldWindowsAndTilemaps();
-        SetMainCallback2(CB2_PokeNav);  // Display PokeNav
+        SetMainCallback2(CB2_InitPokeNav);  // Display PokeNav
 
         return TRUE;
     }
diff --git a/src/text.c b/src/text.c
index a439d3ced8..bdc0f14f79 100644
--- a/src/text.c
+++ b/src/text.c
@@ -12,10 +12,6 @@
 #include "menu.h"
 #include "dynamic_placeholder_text_util.h"
 
-extern u8 GetKeypadIconWidth(u8 keypadIconId);
-extern u16 Font6Func(struct TextPrinter *textPrinter);
-extern u32 GetGlyphWidthFont6(u16 glyphId, bool32 isJapanese);
-
 EWRAM_DATA struct TextPrinter gTempTextPrinter = {0};
 EWRAM_DATA struct TextPrinter gTextPrinters[NUM_TEXT_PRINTERS] = {0};
 
diff --git a/src/trainer_card.c b/src/trainer_card.c
index 4fb30f616c..41bf71cd33 100755
--- a/src/trainer_card.c
+++ b/src/trainer_card.c
@@ -21,6 +21,7 @@
 #include "gpu_regs.h"
 #include "international_string_util.h"
 #include "pokedex.h"
+#include "pokemon_icon.h"
 #include "graphics.h"
 #include "pokemon_icon.h"
 #include "trainer_pokemon_sprites.h"
@@ -89,9 +90,6 @@ struct TrainerCardData
     u8 language;
 };
 
-//external functions
-extern u8 sub_80D30A0(u16);
-
 // EWRAM
 EWRAM_DATA struct TrainerCard gTrainerCards[4] = {0};
 EWRAM_DATA static struct TrainerCardData *sData = NULL;
diff --git a/src/trainer_see.c b/src/trainer_see.c
index bc5d9cbc39..16ea88a455 100644
--- a/src/trainer_see.c
+++ b/src/trainer_see.c
@@ -17,8 +17,6 @@
 #include "constants/event_object_movement_constants.h"
 #include "constants/field_effects.h"
 
-extern void sub_809BE48(u16 npcId);
-
 // this file's functions
 static u8 CheckTrainer(u8 eventObjectId);
 static u8 GetTrainerApproachDistance(struct EventObject *trainerObj);
diff --git a/src/unk_text_util_2.c b/src/unk_text_util_2.c
index bbc256915f..530bd40852 100644
--- a/src/unk_text_util_2.c
+++ b/src/unk_text_util_2.c
@@ -214,7 +214,7 @@ static void DecompressGlyphFont6(u16 glyph)
     gUnknown_03002F90.unk81 = 0x10;
 }
 
-u8 GetGlyphWidthFont6(void)
+u32 GetGlyphWidthFont6(u16 glyphId, bool32 isJapanese)
 {
     return 0x10;
 }
diff --git a/src/water.c b/src/water.c
index c856b9aa45..20bf2542d3 100644
--- a/src/water.c
+++ b/src/water.c
@@ -13,34 +13,33 @@
 #include "constants/battle.h"
 #include "constants/rgb.h"
 
-extern void sub_810721C(struct Sprite *);
-extern void sub_8107228(struct Sprite *);
-extern void sub_8107260(struct Sprite *);
-extern void sub_8107380(struct Sprite *);
-extern void sub_8107408(struct Sprite *);
-extern void sub_8107430(struct Sprite *);
-extern void sub_810744C(struct Sprite *);
-extern void sub_81074E4(struct Sprite *);
-extern void sub_81075EC(struct Sprite *);
-extern void sub_8107674(struct Sprite *);
-extern void sub_8107730(struct Sprite *);
-extern void sub_81077A4(struct Sprite *);
-extern void sub_81077C0(struct Sprite *);
-extern void sub_80A78AC(struct Sprite *);
-extern void sub_8107894(struct Sprite *);
-extern void sub_81078D0(struct Sprite *);
-extern void sub_810790C(struct Sprite *);
-extern void sub_8108034(struct Sprite *);
-extern void sub_8108098(struct Sprite *);
-extern void sub_810851C(struct Sprite *);
-extern void sub_81087C0(struct Sprite *);
-extern void sub_810886C(struct Sprite *);
-extern void sub_8108B2C(struct Sprite *);
-extern void sub_8108B94(struct Sprite *);
-extern void sub_8108BE0(struct Sprite *);
-extern void sub_8108C08(struct Sprite *);
-extern void sub_8108C54(struct Sprite *);
-extern void sub_8108CDC(struct Sprite *);
+void sub_810721C(struct Sprite *);
+void sub_8107228(struct Sprite *);
+void sub_8107260(struct Sprite *);
+void sub_8107380(struct Sprite *);
+void sub_8107408(struct Sprite *);
+void sub_8107430(struct Sprite *);
+void sub_810744C(struct Sprite *);
+void sub_81074E4(struct Sprite *);
+void sub_81075EC(struct Sprite *);
+void sub_8107674(struct Sprite *);
+void sub_8107730(struct Sprite *);
+void sub_81077A4(struct Sprite *);
+void sub_81077C0(struct Sprite *);
+void sub_8107894(struct Sprite *);
+void sub_81078D0(struct Sprite *);
+void sub_810790C(struct Sprite *);
+void sub_8108034(struct Sprite *);
+void sub_8108098(struct Sprite *);
+void sub_810851C(struct Sprite *);
+void sub_81087C0(struct Sprite *);
+void sub_810886C(struct Sprite *);
+void sub_8108B2C(struct Sprite *);
+void sub_8108B94(struct Sprite *);
+void sub_8108BE0(struct Sprite *);
+void sub_8108C08(struct Sprite *);
+void sub_8108C54(struct Sprite *);
+void sub_8108CDC(struct Sprite *);
 void sub_810756C(u8);
 void sub_81076F4(u8);
 void sub_8107B84(u8);