Adds a follower flag define to disable followers on the fly (#6174)

include/config/overworld.h

@@ -60,6 +60,7 @@
 #define OW_FOLLOWERS_WEATHER_FORMS     FALSE      // If TRUE, Castform and Cherrim gain FORM_CHANGE_OVERWORLD_WEATHER, which will make them transform in the overworld based on the weather.
 #define OW_FOLLOWERS_COPY_WILD_PKMN    FALSE      // If TRUE, follower Pokémon that know Transform or have Illusion/Imposter will copy wild Pokémon at random.
 #define OW_BATTLE_ONLY_FORMS           TRUE       // If TRUE, loads overworld sprites for battle-only forms like Mega Evos. Requires OW_POKEMON_OBJECT_EVENTS.
+#define B_FLAG_FOLLOWERS_DISABLED      0          // Enables / Disables followers by using a flag. Helpful to disable followers for a period of time.
 
 // 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.

src/event_object_movement.c

@@ -2179,6 +2179,7 @@ void UpdateFollowingPokemon(void)
     // 3. flag is set
     if (OW_POKEMON_OBJECT_EVENTS == FALSE
      || OW_FOLLOWERS_ENABLED == FALSE
+     || FlagGet(B_FLAG_FOLLOWERS_DISABLED)
      || !GetFollowerInfo(&species, &shiny, &female)
      || SpeciesToGraphicsInfo(species, shiny, female) == NULL
      || (gMapHeader.mapType == MAP_TYPE_INDOOR && SpeciesToGraphicsInfo(species, shiny, female)->oam->size > ST_OAM_SIZE_2)

src/overworld.c

@@ -73,6 +73,8 @@
 #include "constants/trainer_hill.h"
 #include "constants/weather.h"
 
+STATIC_ASSERT((B_FLAG_FOLLOWERS_DISABLED == 0 && !OW_FOLLOWERS_ENABLED), FollowersFlagAssignedWithoutEnablingThem);
+
 struct CableClubPlayer
 {
     u8 playerId;