Fixed Ally Switch breaking Illusion

src/battle_anim_effects_1.c

@@ -6736,6 +6736,7 @@ static void AnimTask_AllySwitchDataSwap(u8 taskId)
     SwapStructData(&gSpecialStatuses[battlerAtk], &gSpecialStatuses[battlerPartner], data, sizeof(struct SpecialStatus));
     SwapStructData(&gProtectStructs[battlerAtk], &gProtectStructs[battlerPartner], data, sizeof(struct ProtectStruct));
     SwapStructData(&gBattleSpritesDataPtr->battlerData[battlerAtk], &gBattleSpritesDataPtr->battlerData[battlerPartner], data, sizeof(struct BattleSpriteInfo));
+    SwapStructData(&gBattleStruct->illusion[battlerAtk], &gBattleStruct->illusion[battlerPartner], data, sizeof(struct Illusion));
 
     SWAP(gBattleSpritesDataPtr->battlerData[battlerAtk].invisible, gBattleSpritesDataPtr->battlerData[battlerPartner].invisible, temp);
     SWAP(gTransformedPersonalities[battlerAtk], gTransformedPersonalities[battlerPartner], temp);

test/battle/move_effect/ally_switch.c

@@ -277,5 +277,21 @@ DOUBLE_BATTLE_TEST("Ally switch swaps opposing sky drop targets if partner is be
     }
 }
 
+DOUBLE_BATTLE_TEST("Ally Switch swaps Illusion data")
+{
+    GIVEN {
+        ASSUME(gMovesInfo[MOVE_ALLY_SWITCH].effect == EFFECT_ALLY_SWITCH);
+        PLAYER(SPECIES_HOOPA);
+        PLAYER(SPECIES_ZOROARK);
+        PLAYER(SPECIES_MAMOSWINE); // the third member here is required for zoroark
+        OPPONENT(SPECIES_WOBBUFFET);
+        OPPONENT(SPECIES_WOBBUFFET);
+    } WHEN {
+        TURN { MOVE(playerLeft, MOVE_ALLY_SWITCH); }
+    } THEN {
+        EXPECT(&gPlayerParty[2] == gBattleStruct->illusion[0].mon);
+    }
+}
+
 // Triple Battles required to test
 //TO_DO_BATTLE_TEST("Ally Switch fails if the user is in the middle of the field in a Triple Battle");