Expanded Pokémon Follower transformation functionality

include/config/overworld.h

@@ -44,8 +44,10 @@
                                                   // 16x32, 32x32, 64x64 etc are fine
 // Follower Pokémon
 #define OW_FOLLOWERS_ENABLED           FALSE      // Enables follower Pokémon, HGSS style. Requires OW_POKEMON_OBJECT_EVENTS. Note that additional scripting may be required for them to be fully supported!
-#define OW_FOLLOWERS_BOBBING           TRUE       // If true, follower pokemon will bob up and down during their idle & walking animations
-#define OW_FOLLOWERS_POKEBALLS         TRUE       // Followers will emerge from the pokeball they are stored in, instead of a normal pokeball
+#define OW_FOLLOWERS_BOBBING           TRUE       // If TRUE, follower Pokémon will bob up and down during their idle & walking animations
+#define OW_FOLLOWERS_POKEBALLS         TRUE       // If TRUE, follower Pokémon will emerge from the Poké Ball they are stored in, instead of a normal Poké Ball
+#define OW_FOLLOWERS_WEATHER_FORMS     FALSE      // If TRUE, follower Pokémon that transform in battle via weather will also transform in the overworld.
+#define OW_FOLLOWERS_COPY_WILD_PKMN    FALSE      // If TRUE, follower Pokémon that know Transform or have Illusion/Imposter will copy wild Pokémon at random.
 
 // Out-of-battle Ability effects
 #define OW_SYNCHRONIZE_NATURE       GEN_LATEST // In Gen8+, if a Pokémon with Synchronize leads the party, wild Pokémon will always have their same Nature as opposed to the 50% chance in previous games. Gift Pokémon excluded.

include/constants/form_change_types.h

@@ -134,4 +134,8 @@
 // param1: amount of days
 #define FORM_CHANGE_DAYS_PASSED                 23
 
+// Form change that activates when overworld weather changes.
+// param1: weather to check.
+#define FORM_CHANGE_OVERWORLD_WEATHER           24
+
 #endif // GUARD_CONSTANTS_FORM_CHANGE_TYPES_H

include/event_object_movement.h

@@ -139,6 +139,7 @@ void ClearObjectEventMovement(struct ObjectEvent *objectEvent, struct Sprite *sp
 void ObjectEventClearHeldMovement(struct ObjectEvent *);
 void ObjectEventClearHeldMovementIfActive(struct ObjectEvent *);
 struct Pokemon *GetFirstLiveMon(void);
+u16 GetOverworldWeatherSpecies(u16 species);
 void UpdateFollowingPokemon(void);
 void RemoveFollowingPokemon(void);
 struct ObjectEvent *GetFollowerObject(void);

src/battle_util.c

@@ -10612,20 +10612,17 @@ bool32 DoesSpeciesUseHoldItemToChangeForm(u16 species, u16 heldItemId)
     u32 i;
     const struct FormChange *formChanges = GetSpeciesFormChanges(species);
 
-    if (formChanges != NULL)
+    for (i = 0; formChanges != NULL && formChanges[i].method != FORM_CHANGE_TERMINATOR; i++)
     {
-        for (i = 0; formChanges[i].method != FORM_CHANGE_TERMINATOR; i++)
+        switch (formChanges[i].method)
         {
-            switch (formChanges[i].method)
-            {
-            case FORM_CHANGE_BATTLE_MEGA_EVOLUTION_ITEM:
-            case FORM_CHANGE_BATTLE_PRIMAL_REVERSION:
-            case FORM_CHANGE_BATTLE_ULTRA_BURST:
-            case FORM_CHANGE_ITEM_HOLD:
-                if (formChanges[i].param1 == heldItemId)
-                    return TRUE;
-                break;
-            }
+        case FORM_CHANGE_BATTLE_MEGA_EVOLUTION_ITEM:
+        case FORM_CHANGE_BATTLE_PRIMAL_REVERSION:
+        case FORM_CHANGE_BATTLE_ULTRA_BURST:
+        case FORM_CHANGE_ITEM_HOLD:
+            if (formChanges[i].param1 == heldItemId)
+                return TRUE;
+            break;
         }
     }
     return FALSE;
@@ -10756,93 +10753,88 @@ u16 GetBattleFormChangeTargetSpecies(u32 battler, u16 method)
     u16 species = gBattleMons[battler].species;
     const struct FormChange *formChanges = GetSpeciesFormChanges(species);
     struct Pokemon *mon = &GetBattlerParty(battler)[gBattlerPartyIndexes[battler]];
-    u16 heldItem;
+    u16 heldItem = gBattleMons[battler].item;
 
-    if (formChanges != NULL)
+    for (i = 0; formChanges != NULL && formChanges[i].method != FORM_CHANGE_TERMINATOR; i++)
     {
-        heldItem = gBattleMons[battler].item;
-
-        for (i = 0; formChanges[i].method != FORM_CHANGE_TERMINATOR; i++)
+        if (method == formChanges[i].method && species != formChanges[i].targetSpecies)
         {
-            if (method == formChanges[i].method && species != formChanges[i].targetSpecies)
+            switch (method)
             {
-                switch (method)
-                {
-                case FORM_CHANGE_BATTLE_MEGA_EVOLUTION_ITEM:
-                case FORM_CHANGE_BATTLE_PRIMAL_REVERSION:
-                case FORM_CHANGE_BATTLE_ULTRA_BURST:
-                    if (heldItem == formChanges[i].param1)
-                        targetSpecies = formChanges[i].targetSpecies;
-                    break;
-                case FORM_CHANGE_BATTLE_MEGA_EVOLUTION_MOVE:
-                    if (gBattleMons[battler].moves[0] == formChanges[i].param1
-                     || gBattleMons[battler].moves[1] == formChanges[i].param1
-                     || gBattleMons[battler].moves[2] == formChanges[i].param1
-                     || gBattleMons[battler].moves[3] == formChanges[i].param1)
-                        targetSpecies = formChanges[i].targetSpecies;
-                    break;
-                case FORM_CHANGE_BATTLE_SWITCH:
-                    if (formChanges[i].param1 == GetBattlerAbility(battler) || formChanges[i].param1 == ABILITY_NONE)
-                        targetSpecies = formChanges[i].targetSpecies;
-                    break;
-                case FORM_CHANGE_BATTLE_HP_PERCENT:
-                    if (formChanges[i].param1 == GetBattlerAbility(battler))
-                    {
-                        // We multiply by 100 to make sure that integer division doesn't mess with the health check.
-                        u32 hpCheck = gBattleMons[battler].hp * 100 * 100 / gBattleMons[battler].maxHP;
-                        switch(formChanges[i].param2)
-                        {
-                        case HP_HIGHER_THAN:
-                            if (hpCheck > formChanges[i].param3 * 100)
-                                targetSpecies = formChanges[i].targetSpecies;
-                            break;
-                        case HP_LOWER_EQ_THAN:
-                            if (hpCheck <= formChanges[i].param3 * 100)
-                                targetSpecies = formChanges[i].targetSpecies;
-                            break;
-                        }
-                    }
-                    break;
-                case FORM_CHANGE_BATTLE_GIGANTAMAX:
-                    if (GetMonData(mon, MON_DATA_GIGANTAMAX_FACTOR))
-                        targetSpecies = formChanges[i].targetSpecies;
-                    break;
-                case FORM_CHANGE_BATTLE_WEATHER:
-                    // Check if there is a required ability and if the battler's ability does not match it
-                    // or is suppressed. If so, revert to the no weather form.
-                    if (formChanges[i].param2
-                        && GetBattlerAbility(battler) != formChanges[i].param2
-                        && formChanges[i].param1 == B_WEATHER_NONE)
-                    {
-                        targetSpecies = formChanges[i].targetSpecies;
-                    }
-                    // We need to revert the weather form if the field is under Air Lock, too.
-                    else if (!WEATHER_HAS_EFFECT && formChanges[i].param1 == B_WEATHER_NONE)
-                    {
-                        targetSpecies = formChanges[i].targetSpecies;
-                    }
-                    // Otherwise, just check for a match between the weather and the form change table.
-                    // Added a check for whether the weather is in effect to prevent end-of-turn soft locks with Cloud Nine / Air Lock
-                    else if (((gBattleWeather & formChanges[i].param1) && WEATHER_HAS_EFFECT)
-                        || (gBattleWeather == B_WEATHER_NONE && formChanges[i].param1 == B_WEATHER_NONE))
+            case FORM_CHANGE_BATTLE_MEGA_EVOLUTION_ITEM:
+            case FORM_CHANGE_BATTLE_PRIMAL_REVERSION:
+            case FORM_CHANGE_BATTLE_ULTRA_BURST:
+                if (heldItem == formChanges[i].param1)
+                    targetSpecies = formChanges[i].targetSpecies;
+                break;
+            case FORM_CHANGE_BATTLE_MEGA_EVOLUTION_MOVE:
+                if (gBattleMons[battler].moves[0] == formChanges[i].param1
+                    || gBattleMons[battler].moves[1] == formChanges[i].param1
+                    || gBattleMons[battler].moves[2] == formChanges[i].param1
+                    || gBattleMons[battler].moves[3] == formChanges[i].param1)
+                    targetSpecies = formChanges[i].targetSpecies;
+                break;
+            case FORM_CHANGE_BATTLE_SWITCH:
+                if (formChanges[i].param1 == GetBattlerAbility(battler) || formChanges[i].param1 == ABILITY_NONE)
+                    targetSpecies = formChanges[i].targetSpecies;
+                break;
+            case FORM_CHANGE_BATTLE_HP_PERCENT:
+                if (formChanges[i].param1 == GetBattlerAbility(battler))
+                {
+                    // We multiply by 100 to make sure that integer division doesn't mess with the health check.
+                    u32 hpCheck = gBattleMons[battler].hp * 100 * 100 / gBattleMons[battler].maxHP;
+                    switch(formChanges[i].param2)
                     {
-                        targetSpecies = formChanges[i].targetSpecies;
+                    case HP_HIGHER_THAN:
+                        if (hpCheck > formChanges[i].param3 * 100)
+                            targetSpecies = formChanges[i].targetSpecies;
+                        break;
+                    case HP_LOWER_EQ_THAN:
+                        if (hpCheck <= formChanges[i].param3 * 100)
+                            targetSpecies = formChanges[i].targetSpecies;
+                        break;
                     }
-                    break;
-                case FORM_CHANGE_BATTLE_TURN_END:
-                case FORM_CHANGE_HIT_BY_MOVE:
-                    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;
-                case FORM_CHANGE_BATTLE_TERASTALLIZATION:
-                    if (GetBattlerTeraType(battler) == formChanges[i].param1)
-                        targetSpecies = formChanges[i].targetSpecies;
-                    break;
                 }
+                break;
+            case FORM_CHANGE_BATTLE_GIGANTAMAX:
+                if (GetMonData(mon, MON_DATA_GIGANTAMAX_FACTOR))
+                    targetSpecies = formChanges[i].targetSpecies;
+                break;
+            case FORM_CHANGE_BATTLE_WEATHER:
+                // Check if there is a required ability and if the battler's ability does not match it
+                // or is suppressed. If so, revert to the no weather form.
+                if (formChanges[i].param2
+                    && GetBattlerAbility(battler) != formChanges[i].param2
+                    && formChanges[i].param1 == B_WEATHER_NONE)
+                {
+                    targetSpecies = formChanges[i].targetSpecies;
+                }
+                // We need to revert the weather form if the field is under Air Lock, too.
+                else if (!WEATHER_HAS_EFFECT && formChanges[i].param1 == B_WEATHER_NONE)
+                {
+                    targetSpecies = formChanges[i].targetSpecies;
+                }
+                // Otherwise, just check for a match between the weather and the form change table.
+                // Added a check for whether the weather is in effect to prevent end-of-turn soft locks with Cloud Nine / Air Lock
+                else if (((gBattleWeather & formChanges[i].param1) && WEATHER_HAS_EFFECT)
+                    || (gBattleWeather == B_WEATHER_NONE && formChanges[i].param1 == B_WEATHER_NONE))
+                {
+                    targetSpecies = formChanges[i].targetSpecies;
+                }
+                break;
+            case FORM_CHANGE_BATTLE_TURN_END:
+            case FORM_CHANGE_HIT_BY_MOVE:
+                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;
+            case FORM_CHANGE_BATTLE_TERASTALLIZATION:
+                if (GetBattlerTeraType(battler) == formChanges[i].param1)
+                    targetSpecies = formChanges[i].targetSpecies;
+                break;
             }
         }
     }

src/data/pokemon/form_change_tables.h

@@ -410,6 +410,13 @@ static const struct FormChange sGlalieFormChangeTable[] = {
 
 #if P_FAMILY_CASTFORM
 static const struct FormChange sCastformFormChangeTable[] = {
+    {FORM_CHANGE_OVERWORLD_WEATHER,             SPECIES_CASTFORM_SUNNY,  WEATHER_SUNNY_CLOUDS},
+    {FORM_CHANGE_OVERWORLD_WEATHER,             SPECIES_CASTFORM_SUNNY,  WEATHER_DROUGHT},
+    {FORM_CHANGE_OVERWORLD_WEATHER,             SPECIES_CASTFORM_RAINY,  WEATHER_RAIN},
+    {FORM_CHANGE_OVERWORLD_WEATHER,             SPECIES_CASTFORM_RAINY,  WEATHER_RAIN_THUNDERSTORM},
+    {FORM_CHANGE_OVERWORLD_WEATHER,             SPECIES_CASTFORM_RAINY,  WEATHER_DOWNPOUR},
+    {FORM_CHANGE_OVERWORLD_WEATHER,             SPECIES_CASTFORM_SNOWY,  WEATHER_SNOW},
+    {FORM_CHANGE_OVERWORLD_WEATHER,             SPECIES_CASTFORM_NORMAL, WEATHER_NONE},
 #if B_WEATHER_FORMS >= GEN_5
     {FORM_CHANGE_BATTLE_WEATHER,                SPECIES_CASTFORM_SUNNY, B_WEATHER_SUN, ABILITY_FORECAST},
     {FORM_CHANGE_BATTLE_WEATHER,                SPECIES_CASTFORM_RAINY, B_WEATHER_RAIN, ABILITY_FORECAST},
@@ -531,6 +538,8 @@ static const struct FormChange sBurmyFormChangeTable[] = {
 
 #if P_FAMILY_CHERUBI
 static const struct FormChange sCherrimFormChangeTable[] = {
+    {FORM_CHANGE_OVERWORLD_WEATHER,             SPECIES_CHERRIM_SUNSHINE, WEATHER_DROUGHT},
+    {FORM_CHANGE_OVERWORLD_WEATHER,             SPECIES_CHERRIM_OVERCAST, WEATHER_NONE},
 #if B_WEATHER_FORMS >= GEN_5
     {FORM_CHANGE_BATTLE_WEATHER,                SPECIES_CHERRIM_SUNSHINE, B_WEATHER_SUN, ABILITY_FLOWER_GIFT},
     {FORM_CHANGE_BATTLE_WEATHER,                SPECIES_CHERRIM_OVERCAST, ~B_WEATHER_SUN, ABILITY_FLOWER_GIFT},

src/event_object_movement.c

@@ -25,6 +25,7 @@
 #include "metatile_behavior.h"
 #include "overworld.h"
 #include "palette.h"
+#include "party_menu.h"
 #include "pokemon.h"
 #include "pokeball.h"
 #include "random.h"
@@ -2018,21 +2019,24 @@ static void RefreshFollowerGraphics(struct ObjectEvent *objEvent)
     }
 }
 
-static u16 GetOverworldCastformSpecies(void)
+u16 GetOverworldWeatherSpecies(u16 species)
 {
-    switch (GetCurrentWeather())
+    u32 i;
+    u32 weather = GetCurrentWeather();
+    const struct FormChange *formChanges = GetSpeciesFormChanges(species);
+
+    for (i = 0; formChanges != NULL && formChanges[i].method != FORM_CHANGE_TERMINATOR; i++)
     {
-    case WEATHER_SUNNY_CLOUDS:
-    case WEATHER_DROUGHT:
-        return SPECIES_CASTFORM_SUNNY;
-    case WEATHER_RAIN:
-    case WEATHER_RAIN_THUNDERSTORM:
-    case WEATHER_DOWNPOUR:
-        return SPECIES_CASTFORM_RAINY;
-    case WEATHER_SNOW:
-        return SPECIES_CASTFORM_SNOWY;
+        // Unlike other form change checks, we don't do the "species != formChanges[i].targetSpecies" check
+        if (formChanges[i].method == FORM_CHANGE_OVERWORLD_WEATHER)
+        {
+            if (formChanges[i].param1 == weather)
+                return formChanges[i].targetSpecies;
+            else if (formChanges[i].param1 == WEATHER_NONE) // Set the default form for weather not defined in form change table
+                species = formChanges[i].targetSpecies;
+        }
     }
-    return SPECIES_CASTFORM_NORMAL;
+    return species;
 }
 
 static bool8 GetMonInfo(struct Pokemon *mon, u16 *species, u8 *form, u8 *shiny)
@@ -2052,8 +2056,8 @@ static bool8 GetMonInfo(struct Pokemon *mon, u16 *species, u8 *form, u8 *shiny)
     case SPECIES_UNOWN:
         *form = GET_UNOWN_LETTER(mon->box.personality);
         break;
-    case SPECIES_CASTFORM: // form is based on overworld weather
-        *species = GetOverworldCastformSpecies();
+    default:
+        *species = GetOverworldWeatherSpecies(*species);
         break;
     }
     return TRUE;
@@ -5207,14 +5211,21 @@ static bool32 EndFollowerTransformEffect(struct ObjectEvent *objectEvent, struct
 static bool32 TryStartFollowerTransformEffect(struct ObjectEvent *objectEvent, struct Sprite *sprite)
 {
     u32 multi;
-    if (GET_BASE_SPECIES_ID(OW_SPECIES(objectEvent)) == SPECIES_CASTFORM
-        && OW_SPECIES(objectEvent) != (multi = GetOverworldCastformSpecies()))
+    struct Pokemon *mon;
+    u32 ability;
+    if (OW_FOLLOWERS_WEATHER_FORMS
+        && DoesSpeciesHaveFormChangeMethod(OW_SPECIES(objectEvent), FORM_CHANGE_BATTLE_WEATHER)
+        && OW_SPECIES(objectEvent) != (multi = GetOverworldWeatherSpecies(OW_SPECIES(objectEvent))))
     {
         sprite->data[7] = TRANSFORM_TYPE_WEATHER << 8;
+        PlaySE(SE_M_MINIMIZE);
         return TRUE;
     }
-    else if ((Random() & 0xFFFF) < 18 && GetLocalWildMon(FALSE)
-            && (OW_SPECIES(objectEvent) == SPECIES_MEW || OW_SPECIES(objectEvent) == SPECIES_DITTO))
+
+    if (OW_FOLLOWERS_COPY_WILD_PKMN
+        && (MonKnowsMove(mon = GetFirstLiveMon(), MOVE_TRANSFORM)
+         || (ability = GetMonAbility(mon)) == ABILITY_IMPOSTER || ability == ABILITY_ILLUSION)
+        && (Random() & 0xFFFF) < 18 && GetLocalWildMon(FALSE))
     {
         sprite->data[7] = TRANSFORM_TYPE_RANDOM_WILD << 8;
         PlaySE(SE_M_MINIMIZE);
@@ -5248,7 +5259,7 @@ static bool8 UpdateFollowerTransformEffect(struct ObjectEvent *objectEvent, stru
             break;
         case TRANSFORM_TYPE_WEATHER:
             multi = objectEvent->graphicsId;
-            objectEvent->graphicsId = GetOverworldCastformSpecies();
+            objectEvent->graphicsId = GetOverworldWeatherSpecies(OW_SPECIES(objectEvent));
             if (!objectEvent->graphicsId)
             {
                 objectEvent->graphicsId = multi;

src/field_weather.c

@@ -198,11 +198,28 @@ void SetNextWeather(u8 weather)
     gWeatherPtr->finishStep = 0;
 }
 
+static void UpdateWeatherForms(void)
+{
+    s32 i;
+    for (i = 0; i < PARTY_SIZE; i++)
+    {
+        struct Pokemon *mon = &gPlayerParty[i];
+        u16 species = GetMonData(mon, MON_DATA_SPECIES);
+        u16 targetSpecies = GetOverworldWeatherSpecies(species);
+        if (species != targetSpecies)
+        {
+            SetMonData(mon, MON_DATA_SPECIES, &targetSpecies);
+            CalculateMonStats(mon);
+        }
+    }
+}
+
 void SetCurrentAndNextWeather(u8 weather)
 {
     PlayRainStoppingSoundEffect();
     gWeatherPtr->currWeather = weather;
     gWeatherPtr->nextWeather = weather;
+    UpdateWeatherForms();
 }
 
 void SetCurrentAndNextWeatherNoDelay(u8 weather)
@@ -212,6 +229,7 @@ void SetCurrentAndNextWeatherNoDelay(u8 weather)
     gWeatherPtr->nextWeather = weather;
     // Overrides the normal delay during screen fading.
     gWeatherPtr->readyForInit = TRUE;
+    UpdateWeatherForms();
 }
 
 static void Task_WeatherInit(u8 taskId)
@@ -239,6 +257,7 @@ static void Task_WeatherMain(u8 taskId)
             gWeatherPtr->palProcessingState = WEATHER_PAL_STATE_CHANGING_WEATHER;
             gWeatherPtr->currWeather = gWeatherPtr->nextWeather;
             gWeatherPtr->weatherChangeComplete = TRUE;
+            UpdateWeatherForms();
         }
     }
     else