diff --git a/data/battle_anim_scripts.s b/data/battle_anim_scripts.s
index 65bac00d73..9ebf32a927 100644
--- a/data/battle_anim_scripts.s
+++ b/data/battle_anim_scripts.s
@@ -863,6 +863,7 @@ Move_ROOST:
 Move_GRAVITY:
 	fadetobg BG_COSMIC
 	waitbgfadein
+	createvisualtask AnimTask_SetAnimTargetToAttackerOpposite, 1
 	playsewithpan SE_M_TAKE_DOWN, SOUND_PAN_ATTACKER
 	createvisualtask AnimTask_ShakeAndSinkMon, 5, ANIM_ATTACKER, 2, 0, 96, 30
 	createvisualtask AnimTask_ShakeAndSinkMon, 5, ANIM_DEF_PARTNER, 2, 0, 96, 30
diff --git a/data/battle_scripts_1.s b/data/battle_scripts_1.s
index e3b34fdda9..007d3649c4 100644
--- a/data/battle_scripts_1.s
+++ b/data/battle_scripts_1.s
@@ -6258,6 +6258,8 @@ BattleScript_CottonDownActivates::
 	savetarget
 	setbyte gBattlerTarget, 0
 BattleScript_CottonDownLoop:
+	getbattlerfainted BS_TARGET
+	jumpifbyte CMP_EQUAL, gBattleCommunication, TRUE, BattleScript_CottonDownLoopIncrement
 	setstatchanger STAT_SPEED, 1, TRUE
 	jumpifbyteequal gBattlerTarget, gEffectBattler, BattleScript_CottonDownLoopIncrement
 	statbuffchange STAT_BUFF_NOT_PROTECT_AFFECTED, BattleScript_CottonDownTargetSpeedCantGoLower
diff --git a/include/battle_ai_util.h b/include/battle_ai_util.h
index db33a7ff11..d4df682c63 100644
--- a/include/battle_ai_util.h
+++ b/include/battle_ai_util.h
@@ -36,6 +36,7 @@ u32 AI_GetMoveAccuracy(u8 battlerAtk, u8 battlerDef, u16 atkAbility, u16 defAbil
 bool32 DoesBattlerIgnoreAbilityChecks(u16 atkAbility, u16 move);
 bool32 AI_WeatherHasEffect(void);
 bool32 CanAttackerFaintTarget(u8 battlerAtk, u8 battlerDef, u8 index, u8 numHits);
+bool32 AI_IsTerrainAffected(u8 battlerId, u32 flags);
 bool32 AI_IsBattlerGrounded(u8 battlerId);
 bool32 HasDamagingMove(u8 battlerId);
 bool32 HasDamagingMoveOfType(u8 battlerId, u8 type);
diff --git a/include/battle_util.h b/include/battle_util.h
index 717017c06c..9aa61221f4 100644
--- a/include/battle_util.h
+++ b/include/battle_util.h
@@ -124,7 +124,7 @@ u16 GetMegaEvolutionSpecies(u16 preEvoSpecies, u16 heldItemId);
 u16 GetWishMegaEvolutionSpecies(u16 preEvoSpecies, u16 moveId1, u16 moveId2, u16 moveId3, u16 moveId4);
 bool32 CanMegaEvolve(u8 battlerId);
 void UndoMegaEvolution(u32 monId);
-void UndoFormChange(u32 monId, u32 side);
+void UndoFormChange(u32 monId, u32 side, bool32 isSwitchingOut);
 bool32 DoBattlersShareType(u32 battler1, u32 battler2);
 bool32 CanBattlerGetOrLoseItem(u8 battlerId, u16 itemId);
 struct Pokemon *GetIllusionMonPtr(u32 battlerId);
diff --git a/include/constants/battle_config.h b/include/constants/battle_config.h
index 0f878d3af6..fd478ae6be 100644
--- a/include/constants/battle_config.h
+++ b/include/constants/battle_config.h
@@ -1,6 +1,8 @@
 #ifndef GUARD_CONSTANTS_BATTLE_CONFIG_H
 #define GUARD_CONSTANTS_BATTLE_CONFIG_H
 
+#include "constants/expansion_branches.h"
+
 // Species with peculiar battle effects.
 #ifndef POKEMON_EXPANSION
     #define SPECIES_DIALGA                  0
diff --git a/include/constants/expansion_branches.h b/include/constants/expansion_branches.h
new file mode 100644
index 0000000000..f88066e684
--- /dev/null
+++ b/include/constants/expansion_branches.h
@@ -0,0 +1,10 @@
+#ifndef GUARD_CONSTANTS_EXPANSION_BRANCHES_H
+#define GUARD_CONSTANTS_EXPANSION_BRANCHES_H
+
+// Branch defines: Used by other branches to detect each other.
+// Each define must be here for each of RHH's branch you have pulled.
+// e.g. If you have both the battle_engine and pokemon_expansion branch,
+//      then both BATTLE_ENGINE and POKEMON_EXPANSION must be defined here.
+#define BATTLE_ENGINE
+
+#endif
diff --git a/include/global.h b/include/global.h
index a5d720eda5..a0aa45d3d0 100644
--- a/include/global.h
+++ b/include/global.h
@@ -10,6 +10,7 @@
 #include "constants/vars.h"
 #include "constants/species.h"
 #include "constants/berry.h"
+#include "constants/expansion_branches.h"
 
 // Prevent cross-jump optimization.
 #define BLOCK_CROSS_JUMP asm("");
@@ -127,12 +128,6 @@
     f;                       \
 })
 
-// Branch defines: Used by other branches to detect each other.
-// Each define must be here for each of RHH's branch you have pulled.
-// e.g. If you have both the battle_engine and pokemon_expansion branch,
-//      then both BATTLE_ENGINE and POKEMON_EXPANSION must be defined here.
-#define BATTLE_ENGINE
-
 #define ROUND_BITS_TO_BYTES(numBits)(((numBits) / 8) + (((numBits) % 8) ? 1 : 0))
 
 #define DEX_FLAGS_NO (ROUND_BITS_TO_BYTES(NUM_SPECIES))
diff --git a/src/battle_ai_main.c b/src/battle_ai_main.c
index 5dc460f6a5..81d97fcab6 100644
--- a/src/battle_ai_main.c
+++ b/src/battle_ai_main.c
@@ -721,22 +721,21 @@ static s16 AI_CheckBadMove(u8 battlerAtk, u8 battlerDef, u16 move, s16 score)
         #endif
         
         // terrain & effect checks
-        if (gFieldStatuses & STATUS_FIELD_MISTY_TERRAIN)
+        if (AI_IsTerrainAffected(battlerDef, STATUS_FIELD_ELECTRIC_TERRAIN))
         {
             if (moveEffect == EFFECT_SLEEP || moveEffect == EFFECT_YAWN)
                 RETURN_SCORE_MINUS(20);
         }
         
-        if (gFieldStatuses & STATUS_FIELD_ELECTRIC_TERRAIN)
+        if (AI_IsTerrainAffected(battlerDef, STATUS_FIELD_MISTY_TERRAIN))
         {
             if (IsNonVolatileStatusMoveEffect(moveEffect) || IsConfusionMoveEffect(moveEffect))
                 RETURN_SCORE_MINUS(20);
         }
         
-        if (gFieldStatuses & STATUS_FIELD_PSYCHIC_TERRAIN)
+        if (AI_IsTerrainAffected(battlerAtk, STATUS_FIELD_PSYCHIC_TERRAIN) && atkPriority > 0)
         {
-            if (atkPriority > 0)
-                RETURN_SCORE_MINUS(20);
+            RETURN_SCORE_MINUS(20);
         }
     } // end check MOVE_TARGET_USER
     
@@ -1641,11 +1640,11 @@ static s16 AI_CheckBadMove(u8 battlerAtk, u8 battlerDef, u16 move, s16 score)
         case EFFECT_TEETER_DANCE:
             if (((gBattleMons[battlerDef].status2 & STATUS2_CONFUSION)
               || (!DoesBattlerIgnoreAbilityChecks(AI_DATA->atkAbility, move) && AI_DATA->defAbility == ABILITY_OWN_TEMPO)
-              || (IsBattlerGrounded(battlerDef) && (gFieldStatuses & STATUS_FIELD_MISTY_TERRAIN))
+              || (IsBattlerGrounded(battlerDef) && AI_IsTerrainAffected(battlerDef, STATUS_FIELD_MISTY_TERRAIN))
               || (DoesSubstituteBlockMove(battlerAtk, battlerDef, move)))
              && ((gBattleMons[AI_DATA->battlerDefPartner].status2 & STATUS2_CONFUSION)
               || (!DoesBattlerIgnoreAbilityChecks(AI_DATA->atkAbility, move) && AI_DATA->defPartnerAbility == ABILITY_OWN_TEMPO)
-              || (IsBattlerGrounded(AI_DATA->battlerDefPartner) && (gFieldStatuses & STATUS_FIELD_MISTY_TERRAIN))
+              || (IsBattlerGrounded(AI_DATA->battlerDefPartner) && AI_IsTerrainAffected(AI_DATA->battlerDefPartner, STATUS_FIELD_MISTY_TERRAIN))
               || (DoesSubstituteBlockMove(battlerAtk, AI_DATA->battlerDefPartner, move))))
             {
                score -= 10;
@@ -3836,7 +3835,7 @@ static s16 AI_CheckViability(u8 battlerAtk, u8 battlerDef, u16 move, s16 score)
             score++;
         break;
     case EFFECT_SAFEGUARD:
-        if (!(gFieldStatuses & STATUS_FIELD_MISTY_TERRAIN) || !IsBattlerGrounded(battlerAtk))
+        if (!AI_IsTerrainAffected(battlerAtk, STATUS_FIELD_MISTY_TERRAIN) || !IsBattlerGrounded(battlerAtk))
             score++;
         //if (CountUsablePartyMons(battlerDef) != 0)
             //score += 8;
diff --git a/src/battle_ai_util.c b/src/battle_ai_util.c
index 5695677bba..600921d97c 100644
--- a/src/battle_ai_util.c
+++ b/src/battle_ai_util.c
@@ -1110,6 +1110,15 @@ u16 AI_GetHoldEffect(u32 battlerId)
     return holdEffect;
 }
 
+bool32 AI_IsTerrainAffected(u8 battlerId, u32 flags)
+{
+    if (gStatuses3[battlerId] & STATUS3_SEMI_INVULNERABLE)
+        return FALSE;
+    else if (!(gFieldStatuses & flags))
+        return FALSE;
+    return AI_IsBattlerGrounded(battlerId);
+}
+
 // different from IsBattlerGrounded in that we don't always know battler's hold effect or ability
 bool32 AI_IsBattlerGrounded(u8 battlerId)
 {
diff --git a/src/battle_anim_mon_movement.c b/src/battle_anim_mon_movement.c
index 9b08352244..75b77494e3 100644
--- a/src/battle_anim_mon_movement.c
+++ b/src/battle_anim_mon_movement.c
@@ -321,6 +321,12 @@ static void AnimTask_ShakeMonInPlace_Step(u8 taskId)
 void AnimTask_ShakeAndSinkMon(u8 taskId)
 {
     u8 spriteId = GetAnimBattlerSpriteId(gBattleAnimArgs[0]);
+
+    if (spriteId == SPRITE_NONE)
+    {
+        DestroyAnimVisualTask(taskId);
+        return;
+    }
     gSprites[spriteId].pos2.x = gBattleAnimArgs[1];
     gTasks[taskId].data[0] = spriteId;
     gTasks[taskId].data[1] = gBattleAnimArgs[1];
diff --git a/src/battle_anim_utility_funcs.c b/src/battle_anim_utility_funcs.c
index 4d18d04fa2..0f2c8bda80 100644
--- a/src/battle_anim_utility_funcs.c
+++ b/src/battle_anim_utility_funcs.c
@@ -1084,3 +1084,9 @@ void AnimTask_SetInvisible(u8 taskId)
     gSprites[spriteId].invisible = gBattleSpritesDataPtr->battlerData[battlerId].invisible = gBattleAnimArgs[1];
     DestroyAnimVisualTask(taskId);
 }
+
+void AnimTask_SetAnimTargetToAttackerOpposite(u8 taskId)
+{
+    gBattleAnimTarget = BATTLE_OPPOSITE(gBattleAnimAttacker);
+    DestroyAnimVisualTask(taskId);
+}
diff --git a/src/battle_main.c b/src/battle_main.c
index 6befbfbf5a..c728ae266a 100644
--- a/src/battle_main.c
+++ b/src/battle_main.c
@@ -3123,7 +3123,7 @@ void FaintClearSetData(void)
     ClearBattlerMoveHistory(gActiveBattler);
     ClearBattlerAbilityHistory(gActiveBattler);
     ClearBattlerItemEffectHistory(gActiveBattler);
-    UndoFormChange(gBattlerPartyIndexes[gActiveBattler], GET_BATTLER_SIDE(gActiveBattler));
+    UndoFormChange(gBattlerPartyIndexes[gActiveBattler], GET_BATTLER_SIDE(gActiveBattler), FALSE);
     if (GetBattlerSide(gActiveBattler) == B_SIDE_PLAYER)
         UndoMegaEvolution(gBattlerPartyIndexes[gActiveBattler]);
 }
@@ -4888,7 +4888,7 @@ static void HandleEndTurn_FinishBattle(void)
         for (i = 0; i < PARTY_SIZE; i++)
         {
             UndoMegaEvolution(i);
-            UndoFormChange(i, B_SIDE_PLAYER);
+            UndoFormChange(i, B_SIDE_PLAYER, FALSE);
         }
         gBattleMainFunc = FreeResetData_ReturnToOvOrDoEvolutions;
         gCB2_AfterEvolution = BattleMainCB2;
diff --git a/src/battle_script_commands.c b/src/battle_script_commands.c
index f5f093cc5c..cb2f791919 100644
--- a/src/battle_script_commands.c
+++ b/src/battle_script_commands.c
@@ -12098,6 +12098,7 @@ static void Cmd_handleballthrow(void)
         {
             BtlController_EmitBallThrowAnim(0, BALL_3_SHAKES_SUCCESS);
             MarkBattlerForControllerExec(gActiveBattler);
+            UndoFormChange(gBattlerPartyIndexes[gBattlerTarget], GET_BATTLER_SIDE(gBattlerTarget));
             gBattlescriptCurrInstr = BattleScript_SuccessBallThrow;
             SetMonData(&gEnemyParty[gBattlerPartyIndexes[gBattlerTarget]], MON_DATA_POKEBALL, &gLastUsedItem);
 
@@ -12142,6 +12143,7 @@ static void Cmd_handleballthrow(void)
                 if (IsCriticalCapture())
                     gBattleSpritesDataPtr->animationData->criticalCaptureSuccess = 1;
 
+                UndoFormChange(gBattlerPartyIndexes[gBattlerTarget], GET_BATTLER_SIDE(gBattlerTarget));
                 gBattlescriptCurrInstr = BattleScript_SuccessBallThrow;
                 SetMonData(&gEnemyParty[gBattlerPartyIndexes[gBattlerTarget]], MON_DATA_POKEBALL, &gLastUsedItem);
                 if (CalculatePlayerPartyCount() == PARTY_SIZE)
diff --git a/src/battle_util.c b/src/battle_util.c
index 7a86b659f8..4ed7572c4a 100644
--- a/src/battle_util.c
+++ b/src/battle_util.c
@@ -492,7 +492,7 @@ void HandleAction_Switch(void)
     if (gBattleResults.playerSwitchesCounter < 255)
         gBattleResults.playerSwitchesCounter++;
 
-    UndoFormChange(gBattlerPartyIndexes[gBattlerAttacker], GetBattlerSide(gBattlerAttacker));
+    UndoFormChange(gBattlerPartyIndexes[gBattlerAttacker], GetBattlerSide(gBattlerAttacker), TRUE);
 }
 
 void HandleAction_UseItem(void)
@@ -8333,14 +8333,14 @@ void UndoMegaEvolution(u32 monId)
     }
 }
 
-void UndoFormChange(u32 monId, u32 side)
+void UndoFormChange(u32 monId, u32 side, bool32 isSwitchingOut)
 {
     u32 i, currSpecies;
     struct Pokemon *party = (side == B_SIDE_PLAYER) ? gPlayerParty : gEnemyParty;
     static const u16 species[][2] = // changed form id, default form id
     {
-        {SPECIES_AEGISLASH_BLADE, SPECIES_AEGISLASH},
         {SPECIES_MIMIKYU_BUSTED, SPECIES_MIMIKYU},
+        {SPECIES_AEGISLASH_BLADE, SPECIES_AEGISLASH},
         {SPECIES_DARMANITAN_ZEN_MODE, SPECIES_DARMANITAN},
         {SPECIES_MINIOR, SPECIES_MINIOR_CORE_RED},
         {SPECIES_MINIOR_METEOR_BLUE, SPECIES_MINIOR_CORE_BLUE},
@@ -8352,8 +8352,13 @@ void UndoFormChange(u32 monId, u32 side)
         {SPECIES_WISHIWASHI_SCHOOL, SPECIES_WISHIWASHI},
     };
 
+    if (isSwitchingOut) // Don't revert Mimikyu Busted when switching out
+        i = 1;
+    else
+        i = 0;
+
     currSpecies = GetMonData(&party[monId], MON_DATA_SPECIES, NULL);
-    for (i = 0; i < ARRAY_COUNT(species); i++)
+    for (; i < ARRAY_COUNT(species); i++)
     {
         if (currSpecies == species[i][0])
         {