Added B_DOUBLE_WILD_REQUIRE_2_MONS to use of B_DOUBLE_WILD_CHANCE even when there is only one Pokémon in the party (#2878)

include/config/battle.h

@@ -183,6 +183,7 @@
 
 // Other settings
 #define B_DOUBLE_WILD_CHANCE        0          // % chance of encountering two Pokémon in a Wild Encounter.
+#define B_DOUBLE_WILD_REQUIRE_2_MONS    FALSE   // If set to TRUE, Wild Double Battles will default to Single Battles when the player only has 1 usuable Pokémon, ignoring B_DOUBLE_WILD_CHANCE and B_FLAG_FORCE_DOUBLE_WILD. 
 #define B_MULTI_BATTLE_WHITEOUT     GEN_LATEST // In Gen4+, multi battles end when the Player and also their Partner don't have any more Pokémon to fight.
 #define B_EVOLUTION_AFTER_WHITEOUT  GEN_LATEST // In Gen6+, Pokemon that qualify for evolution after battle will evolve even if the player loses.
 #define B_WILD_NATURAL_ENEMIES      TRUE       // If set to TRUE, certain wild mon species will attack other species when partnered in double wild battles (eg. Zangoose vs Seviper)

src/wild_encounter.c

@@ -1097,7 +1097,11 @@ static void ApplyCleanseTagEncounterRateMod(u32 *encRate)
 
 bool8 TryDoDoubleWildBattle(void)
 {
+#if B_DOUBLE_WILD_REQUIRE_2_MONS == TRUE
     if (GetSafariZoneFlag() || GetMonsStateToDoubles() != PLAYER_HAS_TWO_USABLE_MONS)
+#else
+    if (GetSafariZoneFlag())
+#endif
         return FALSE;
 #if B_FLAG_FORCE_DOUBLE_WILD != 0
     else if (FlagGet(B_FLAG_FORCE_DOUBLE_WILD))