Add the Let's Go evolution method (#4758)

* Add overworld step evolution method

* Increase evolutionTracker bits from 9 to 10

* Implement tracker increase

* Remove leftover NDEBUG activation

* Reset evolution tracker data upon evolution

* Revert an accidental change to unrelated code

* Add missing break in switch case, oops

include/constants/pokemon.h

@@ -297,6 +297,7 @@
 #define EVO_RECOIL_DAMAGE_FEMALE          49     // Pokémon levels up after having suffered specified amount of non-fainting recoil damage as a female
 #define EVO_ITEM_COUNT_999                50     // Pokémon levels up after trainer has collected 999 of a specific item
 #define EVO_DEFEAT_WITH_ITEM              51     // Pokémon levels up after having defeat 3 Pokémon of the same species holding the specified item
+#define EVO_OVERWORLD_STEPS               52     // Pokémon levels up after having taken a specific amount of steps in the overworld
 
 // Evolution 'modes,' for GetEvolutionTargetSpecies
 #define EVO_MODE_NORMAL            0

include/pokemon.h

@@ -138,8 +138,7 @@ struct PokemonSubstruct1
     u16 move1:11; // 2047 moves.
     u16 evolutionTracker1:5;
     u16 move2:11; // 2047 moves.
-    u16 evolutionTracker2:4;
+    u16 evolutionTracker2:5;
-    u16 unused_02:1;
     u16 move3:11; // 2047 moves.
     u16 unused_04:5;
     u16 move4:11; // 2047 moves.

src/battle_script_commands.c

@@ -16899,8 +16899,8 @@ static void TryUpdateEvolutionTracker(u32 evolutionMethod, u32 upAmount, u16 use
 
             if (evolutions[i].method == evolutionMethod)
             {
-                // We only have 9 bits to use
+                // We only have 10 bits to use
-                u16 val = min(511, GetMonData(&gPlayerParty[gBattlerPartyIndexes[gBattlerAttacker]], MON_DATA_EVOLUTION_TRACKER) + upAmount);
+                u16 val = min(1023, GetMonData(&gPlayerParty[gBattlerPartyIndexes[gBattlerAttacker]], MON_DATA_EVOLUTION_TRACKER) + upAmount);
                 // Reset progress if you faint for the recoil method.
                 switch (evolutionMethod)
                 {

src/data/pokemon/species_info/gen_9_families.h

@@ -969,7 +969,7 @@ const struct SpeciesInfo gSpeciesInfoGen9[] =
         FOOTPRINT(Pawmo)
         .levelUpLearnset = sPawmoLevelUpLearnset,
         .teachableLearnset = sPawmoTeachableLearnset,
-        .evolutions = EVOLUTION({EVO_NONE, 0, SPECIES_PAWMOT}),
+        .evolutions = EVOLUTION({EVO_OVERWORLD_STEPS, 1000, SPECIES_PAWMOT}),
     },
 
     [SPECIES_PAWMOT] =
@@ -2481,7 +2481,7 @@ const struct SpeciesInfo gSpeciesInfoGen9[] =
         .levelUpLearnset = sBramblinLevelUpLearnset,
         .teachableLearnset = sBramblinTeachableLearnset,
         .eggMoveLearnset = sBramblinEggMoveLearnset,
-        .evolutions = EVOLUTION({EVO_NONE, 0, SPECIES_BRAMBLEGHAST}),
+        .evolutions = EVOLUTION({EVO_OVERWORLD_STEPS, 1000, SPECIES_BRAMBLEGHAST}),
     },
 
     [SPECIES_BRAMBLEGHAST] =
@@ -2860,7 +2860,7 @@ const struct SpeciesInfo gSpeciesInfoGen9[] =
         .levelUpLearnset = sRellorLevelUpLearnset,
         .teachableLearnset = sRellorTeachableLearnset,
         .eggMoveLearnset = sRellorEggMoveLearnset,
-        .evolutions = EVOLUTION({EVO_NONE, 0, SPECIES_RABSCA}),
+        .evolutions = EVOLUTION({EVO_OVERWORLD_STEPS, 1000, SPECIES_RABSCA}),
     },
 
     [SPECIES_RABSCA] =

src/evolution_scene.c

@@ -769,11 +769,13 @@ static void Task_EvolutionScene(u8 taskId)
     case EVOSTATE_SET_MON_EVOLVED:
         if (IsCryFinished())
         {
+            u32 zero = 0;
             StringExpandPlaceholders(gStringVar4, gText_CongratsPkmnEvolved);
             BattlePutTextOnWindow(gStringVar4, B_WIN_MSG);
             PlayBGM(MUS_EVOLVED);
             gTasks[taskId].tState++;
             SetMonData(mon, MON_DATA_SPECIES, (void *)(&gTasks[taskId].tPostEvoSpecies));
+            SetMonData(mon, MON_DATA_EVOLUTION_TRACKER, &zero);
             CalculateMonStats(mon);
             EvolutionRenameMon(mon, gTasks[taskId].tPreEvoSpecies, gTasks[taskId].tPostEvoSpecies);
             GetSetPokedexFlag(SpeciesToNationalPokedexNum(gTasks[taskId].tPostEvoSpecies), FLAG_SET_SEEN);
@@ -1188,11 +1190,13 @@ static void Task_TradeEvolutionScene(u8 taskId)
     case T_EVOSTATE_SET_MON_EVOLVED:
         if (IsCryFinished())
         {
+            u32 zero = 0;
             StringExpandPlaceholders(gStringVar4, gText_CongratsPkmnEvolved);
             DrawTextOnTradeWindow(0, gStringVar4, 1);
             PlayFanfare(MUS_EVOLVED);
             gTasks[taskId].tState++;
             SetMonData(mon, MON_DATA_SPECIES, (&gTasks[taskId].tPostEvoSpecies));
+            SetMonData(mon, MON_DATA_EVOLUTION_TRACKER, &zero);
             CalculateMonStats(mon);
             EvolutionRenameMon(mon, gTasks[taskId].tPreEvoSpecies, gTasks[taskId].tPostEvoSpecies);
             GetSetPokedexFlag(SpeciesToNationalPokedexNum(gTasks[taskId].tPostEvoSpecies), FLAG_SET_SEEN);

src/field_control_avatar.c

@@ -69,6 +69,7 @@ static bool8 TryStartWarpEventScript(struct MapPosition *, u16);
 static bool8 TryStartMiscWalkingScripts(u16);
 static bool8 TryStartStepCountScript(u16);
 static void UpdateFriendshipStepCounter(void);
+static void UpdateLetsGoEvolutionTracker(void);
 #if OW_POISON_DAMAGE < GEN_5
 static bool8 UpdatePoisonStepCounter(void);
 #endif // OW_POISON_DAMAGE
@@ -565,6 +566,7 @@ static bool8 TryStartStepCountScript(u16 metatileBehavior)
     IncrementRematchStepCounter();
     UpdateFriendshipStepCounter();
     UpdateFarawayIslandStepCounter();
+    UpdateLetsGoEvolutionTracker();
 
     if (!(gPlayerAvatar.flags & PLAYER_AVATAR_FLAG_FORCED_MOVE) && !MetatileBehavior_IsForcedMovementTile(metatileBehavior))
     {
@@ -658,6 +660,28 @@ static void UpdateFriendshipStepCounter(void)
     }
 }
 
+static void UpdateLetsGoEvolutionTracker(void)
+{
+    u32 i;
+    u16 count;
+    struct Pokemon *followingMon = GetFirstLiveMon();
+    const struct Evolution *evolutions = GetSpeciesEvolutions(GetMonData(followingMon, MON_DATA_SPECIES));
+
+    if (evolutions == NULL)
+        return;
+
+    for (i = 0; evolutions[i].method != EVOLUTIONS_END; i++)
+    {
+        if (evolutions[i].method != EVO_OVERWORLD_STEPS || SanitizeSpeciesId(evolutions[i].targetSpecies) == SPECIES_NONE)
+            continue;
+
+        // We only have 10 bits to use
+        count = min(1023, GetMonData(followingMon, MON_DATA_EVOLUTION_TRACKER) + 1);
+        SetMonData(followingMon, MON_DATA_EVOLUTION_TRACKER, &count);
+        return;
+    }
+}
+
 void ClearPoisonStepCounter(void)
 {
     VarSet(VAR_POISON_STEP_COUNTER, 0);

src/pokedex_plus_hgss.c

@@ -250,6 +250,7 @@ static const u8 sText_EVO_RECOIL_DAMAGE_MALE[] = _("{LV}{UP_ARROW} with {STR_VAR
 static const u8 sText_EVO_RECOIL_DAMAGE_FEMALE[] = _("{LV}{UP_ARROW} with {STR_VAR_2} recoil, female");
 static const u8 sText_EVO_ITEM_COUNT_999[] = _("{LV}{UP_ARROW} with 999 {STR_VAR_2} in bag");
 static const u8 sText_EVO_DEFEAT_WITH_ITEM[] = _("{LV}{UP_ARROW} defeating {STR_VAR_3} holding {STR_VAR_2}");
+static const u8 sText_EVO_OVERWORLD_STEPS[] = _("{LV}{UP_ARROW} after {STR_VAR_2} steps");
 static const u8 sText_EVO_UNKNOWN[] = _("Method unknown");
 static const u8 sText_EVO_NONE[] = _("{STR_VAR_1} has no evolution.");
 
@@ -6628,12 +6629,16 @@ static void PrintEvolutionTargetSpeciesAndMethod(u8 taskId, u16 species, u8 dept
             CopyItemName(item, gStringVar2);
             StringExpandPlaceholders(gStringVar4, sText_EVO_ITEM_COUNT_999);
             break;
-        case EVO_DEFEAT_WITH_ITEM:
+         case EVO_DEFEAT_WITH_ITEM:
             item = evolutions[i].param;
             CopyItemName(item, gStringVar2);
             StringCopy(gStringVar3, GetSpeciesName(species));
             StringExpandPlaceholders(gStringVar4, sText_EVO_DEFEAT_WITH_ITEM);
             break;
+        case EVO_OVERWORLD_STEPS:
+            ConvertIntToDecimalStringN(gStringVar2, evolutions[i].param, STR_CONV_MODE_LEADING_ZEROS, 4);
+            StringExpandPlaceholders(gStringVar4, sText_EVO_OVERWORLD_STEPS);
+            break;
         default:
             StringExpandPlaceholders(gStringVar4, sText_EVO_UNKNOWN);
             break;

src/pokemon.c

@@ -2383,8 +2383,8 @@ u32 GetMonData2(struct Pokemon *mon, s32 field)
 struct EvolutionTrackerBitfield
 {
     u16 a: 5;
-    u16 b: 4;
+    u16 b: 5;
-    u16 unused: 7;
+    u16 unused: 6;
 };
 
 union EvolutionTracker
@@ -4688,6 +4688,10 @@ u16 GetEvolutionTargetSpecies(struct Pokemon *mon, u8 mode, u16 evolutionItem, s
                 if (evolutionTracker >= 3)
                     targetSpecies = evolutions[i].targetSpecies;
                 break;
+            case EVO_OVERWORLD_STEPS:
+                if (evolutionTracker >= evolutions[i].param)
+                    targetSpecies = evolutions[i].targetSpecies;
+                break;
             }
         }
         break;