Add status form change

asm/macros/battle_script.inc

@@ -1557,6 +1557,10 @@
 	.4byte \failInstr
 	.endm
 
+	.macro trytriggerstatusform
+	callnative BS_TryTriggerStatusForm
+	.endm
+
 @ various command changed to more readable macros
 	.macro cancelmultiturnmoves battler:req
 	various \battler, VARIOUS_CANCEL_MULTI_TURN_MOVES

data/battle_scripts_1.s

@@ -8342,6 +8342,8 @@ BattleScript_MoveEffectSleep::
 BattleScript_UpdateEffectStatusIconRet::
 	updatestatusicon BS_EFFECT_BATTLER
 	waitstate
+	trytriggerstatusform
+	flushtextbox
 	return
 
 BattleScript_YawnMakesAsleep::

include/constants/form_change_types.h

@@ -116,4 +116,8 @@
 // param1: multichoice list (starting at 0).
 #define FORM_CHANGE_ITEM_USE_MULTICHOICE        19
 
+// Form change that activates when inflicted with a specific status
+// param1: status
+#define FORM_CHANGE_STATUS                      20
+
 #endif // GUARD_CONSTANTS_FORM_CHANGE_TYPES_H

src/battle_script_commands.c

@@ -16496,3 +16496,16 @@ void BS_TryDefog(void)
             gBattlescriptCurrInstr = cmd->failInstr;
     }
 }
+
+void BS_TryTriggerStatusForm(void)
+{
+    NATIVE_ARGS();
+    if (TryBattleFormChange(gBattlerTarget, FORM_CHANGE_STATUS))
+    {
+        gBattleScripting.battler = gBattlerTarget;
+        BattleScriptPush(cmd->nextInstr);
+        gBattlescriptCurrInstr = BattleScript_TargetFormChangeWithStringNoPopup;
+        return;
+    }
+    gBattlescriptCurrInstr = cmd->nextInstr;
+}

src/battle_util.c

@@ -10494,6 +10494,10 @@ u16 GetBattleFormChangeTargetSpecies(u32 battler, u16 method)
                     if (formChanges[i].param1 == GetBattlerAbility(battler))
                         targetSpecies = formChanges[i].targetSpecies;
                     break;
+                case FORM_CHANGE_STATUS:
+                    if (gBattleMons[battler].status1 & formChanges[i].param1)
+                        targetSpecies = formChanges[i].targetSpecies;
+                    break;
                 }
             }
         }

src/data/pokemon/form_change_tables.h

@@ -489,6 +489,7 @@ static const struct FormChange sShayminFormChangeTable[] = {
     {FORM_CHANGE_ITEM_USE,    SPECIES_SHAYMIN_SKY, ITEM_GRACIDEA, DAY},
     {FORM_CHANGE_WITHDRAW,    SPECIES_SHAYMIN_LAND},
     {FORM_CHANGE_TIME_OF_DAY, SPECIES_SHAYMIN_LAND, NIGHT},
+    {FORM_CHANGE_STATUS,      SPECIES_SHAYMIN_LAND, (STATUS1_FREEZE | STATUS1_FROSTBITE)},
     {FORM_CHANGE_TERMINATOR},
 };
 #endif //P_FAMILY_SHAYMIN

src/pokemon.c

@@ -5821,6 +5821,7 @@ u16 GetFormChangeTargetSpeciesBoxMon(struct BoxPokemon *boxMon, u16 method, u32
                     break;
                 case FORM_CHANGE_WITHDRAW:
                 case FORM_CHANGE_FAINT:
+                case FORM_CHANGE_STATUS:
                     targetSpecies = formChanges[i].targetSpecies;
                     break;
                 case FORM_CHANGE_TIME_OF_DAY:

test/battle/form_change/status.c

@@ -0,0 +1,15 @@
+#include "global.h"
+#include "test/battle.h"
+
+SINGLE_BATTLE_TEST("Shaymin-Sky reverts to Shaymin-Land when frozen or frostbitten")
+{
+    ASSUME(gBattleMoves[MOVE_POWDER_SNOW].effect == ((B_USE_FROSTBITE == TRUE) ? EFFECT_FROSTBITE_HIT : EFFECT_FREEZE_HIT));
+    GIVEN {
+        PLAYER(SPECIES_SHAYMIN_SKY);
+        OPPONENT(SPECIES_WOBBUFFET);
+    } WHEN {
+        TURN { MOVE(opponent, MOVE_POWDER_SNOW); }
+    } THEN {
+        EXPECT_EQ(player->species, SPECIES_SHAYMIN_LAND);
+    }
+}