add eject button

data/battle_scripts_1.s

@@ -7803,7 +7803,7 @@ BattleScript_AnnounceAirLockCloudNine::
 	end3
 
 BattleScript_RedCardActivates::
-	jumpifcantswitch SWITCH_IGNORE_ESCAPE_PREVENTION | BS_ATTACKER, BattleScript_RedCardEnd
+	jumpifcantswitch BS_ATTACKER, BattleScript_RedCardEnd
 	playanimation BS_SCRIPTING, B_ANIM_HELD_ITEM_EFFECT, NULL
 	printstring STRINGID_REDCARDACTIVATE
 	waitmessage 0x40
@@ -7829,3 +7829,24 @@ BattleScript_RedCardSuctionCups:
 	swapattackerwithtarget
 	return
 
+BattleScript_EjectButtonActivates::
+	jumpifcantswitch BS_SCRIPTING, BattleScript_EjectButtonEnd
+	makevisible BS_ATTACKER
+	playanimation BS_SCRIPTING, B_ANIM_HELD_ITEM_EFFECT, NULL
+	printstring STRINGID_EJECTBUTTONACTIVATE
+	waitmessage 0x40
+	removeitem BS_SCRIPTING
+	openpartyscreen BS_SCRIPTING, BattleScript_EjectButtonEnd
+	switchoutabilities BS_SCRIPTING
+	waitstate
+	switchhandleorder BS_SCRIPTING 0x2
+	returntoball BS_SCRIPTING
+	getswitchedmondata BS_SCRIPTING
+	switchindataupdate BS_SCRIPTING
+	hpthresholds BS_SCRIPTING
+	printstring 0x3
+	switchinanim BS_SCRIPTING 0x1
+	waitstate
+	switchineffects BS_SCRIPTING
+BattleScript_EjectButtonEnd:
+	return

include/battle_ai_script_commands.h

@@ -23,5 +23,6 @@ void RecordAbilityBattle(u8 battlerId, u16 abilityId);
 void ClearBattlerAbilityHistory(u8 battlerId);
 void RecordItemEffectBattle(u8 battlerId, u8 itemEffect);
 void ClearBattlerItemEffectHistory(u8 battlerId);
+s32 CountUsablePartyMons(u8 battlerId);
 
 #endif // GUARD_BATTLE_AI_SCRIPT_COMMANDS_H

include/battle_scripts.h

@@ -353,5 +353,6 @@ extern const u8 BattleScript_CheekPouchActivates[];
 extern const u8 BattleScript_AnnounceAirLockCloudNine[];
 extern const u8 BattleScript_AttackerItemStatRaise[];
 extern const u8 BattleScript_RedCardActivates[];
+extern const u8 BattleScript_EjectButtonActivates[];
 
 #endif // GUARD_BATTLE_SCRIPTS_H

include/constants/battle_string_ids.h

@@ -559,8 +559,9 @@
 #define STRINGID_COMATOSEENTERS 555
 #define STRINGID_SCREENCLEANERENTERS 556
 #define STRINGID_REDCARDACTIVATE 557
+#define STRINGID_EJECTBUTTONACTIVATE 558
 
-#define BATTLESTRINGS_COUNT     558
+#define BATTLESTRINGS_COUNT     559
 
 //// multichoice message IDs
 // switch in ability message

src/battle_ai_script_commands.c

@@ -54,7 +54,6 @@ static void RecordLastUsedMoveByTarget(void);
 static void BattleAI_DoAIProcessing(void);
 static void AIStackPushVar(const u8 *);
 static bool8 AIStackPop(void);
-static s32 CountUsablePartyMons(u8 battlerId);
 static s32 AI_GetAbility(u32 battlerId, bool32 guess);
 
 static void Cmd_if_random_less_than(void);
@@ -1614,7 +1613,7 @@ static void Cmd_nullsub_2B(void)
 {
 }
 
-static s32 CountUsablePartyMons(u8 battlerId)
+s32 CountUsablePartyMons(u8 battlerId)
 {
     s32 battlerOnField1, battlerOnField2, i, ret;
     struct Pokemon *party;

src/battle_message.c

@@ -686,9 +686,11 @@ static const u8 sText_AuraBreakActivates[] = _("{B_SCR_ACTIVE_NAME_WITH_PREFIX}
 static const u8 sText_ComatoseActivates[] = _("{B_SCR_ACTIVE_NAME_WITH_PREFIX} is drowsing!");
 static const u8 sText_ScreenCleanerActivates[] = _("All screens on the field were\ncleansed!");
 static const u8 sText_RedCardActivate[] = _("{B_SCR_ACTIVE_NAME_WITH_PREFIX} held up its {B_LAST_ITEM}\nagainst {B_ATK_NAME_WITH_PREFIX}!");
+static const u8 sText_EjectButtonActivate[] = _("{B_SCR_ACTIVE_NAME_WITH_PREFIX} is switched\nout with the {B_LAST_ITEM}!");
 
 const u8 *const gBattleStringsTable[BATTLESTRINGS_COUNT] =
 {
+    [STRINGID_EJECTBUTTONACTIVATE - 12] = sText_EjectButtonActivate,
     [STRINGID_REDCARDACTIVATE - 12] = sText_RedCardActivate,
     [STRINGID_STATWASNOTLOWERED - 12] = sText_StatWasNotLowered,
     [STRINGID_CLOAKEDINAFREEZINGLIGHT - 12] = sText_CloakedInAFreezingLight,

src/battle_script_commands.c

@@ -5010,6 +5010,36 @@ static void Cmd_moveend(void)
             gBattleScripting.moveendState++;
             break;
         case MOVEEND_EJECT_BUTTON:
+            if (gCurrentMove != MOVE_DRAGON_TAIL
+              && gCurrentMove != MOVE_CIRCLE_THROW
+              && !(gMoveResultFlags & MOVE_RESULT_NO_EFFECT)
+              && IsBattlerAlive(gBattlerAttacker)
+              && !TestSheerForceFlag(gBattlerAttacker, gCurrentMove)
+              && (GetBattlerSide(gBattlerAttacker) == B_SIDE_PLAYER || (gBattleTypeFlags & BATTLE_TYPE_TRAINER)))
+            {
+                u8 battlers[4] = {0, 1, 2, 3};
+                SortBattlersBySpeed(battlers, FALSE);
+                for (i = 0; i < gBattlersCount; i++)
+                {
+                    u8 battler = battlers[i];
+                    // attacker is the damage-dealer, battler is mon to be switched out
+                    if (IsBattlerAlive(battler)
+                      && GetBattlerHoldEffect(battler, TRUE) == HOLD_EFFECT_EJECT_BUTTON
+                      && !DoesSubstituteBlockMove(gCurrentMove, gBattlerAttacker, battler)
+                      && (gSpecialStatuses[battler].physicalDmg != 0 || gSpecialStatuses[battler].specialDmg != 0)
+                      && CountUsablePartyMons(battler) > 0)
+                    {
+                        gActiveBattler = gBattleScripting.battler = battler;
+                        gLastUsedItem = gBattleMons[battler].item;
+                        if (gBattleMoves[gCurrentMove].effect == EFFECT_HIT_ESCAPE)
+                            gBattlescriptCurrInstr = BattleScript_MoveEnd;  // prevent user switch-in selection
+                        BattleScriptPushCursor();
+                        gBattlescriptCurrInstr = BattleScript_EjectButtonActivates;
+                        effect = TRUE;
+                        break; // only the fastest Eject Button activates
+                    }
+                }
+            }
             gBattleScripting.moveendState++;
             break;
         case MOVEEND_RED_CARD:
@@ -5030,7 +5060,8 @@ static void Cmd_moveend(void)
                       && IsBattlerAlive(battler)
                       && !DoesSubstituteBlockMove(gCurrentMove, gBattlerAttacker, battler)
                       && GetBattlerHoldEffect(battler, TRUE) == HOLD_EFFECT_RED_CARD
-                      && (gSpecialStatuses[battler].physicalDmg != 0 || gSpecialStatuses[battler].specialDmg != 0))
+                      && (gSpecialStatuses[battler].physicalDmg != 0 || gSpecialStatuses[battler].specialDmg != 0)
+                      && CountUsablePartyMons(battler) > 0)
                     {
                         gLastUsedItem = gBattleMons[battler].item;
                         gActiveBattler = gBattleScripting.battler = battler;    // battler with red card