config option for terrain bg change

include/constants/battle_config.h

@@ -164,5 +164,6 @@
 #define B_NEW_SURF_PARTICLE_PALETTE     TRUE    // If set to TRUE, it updates Surf's wave palette.
 
 #define HIDE_HEALTHBOXES_DURING_ANIMS   TRUE    //if TRUE, hides healthboxes during move animations
+#define B_TERRAIN_BG_CHANGE             TRUE    //if TRUE, terrain moves permanently change the default battle bg until the effect fades
 
 #endif // GUARD_CONSTANTS_BATTLE_CONFIG_H

src/battle_anim.c

@@ -3204,8 +3204,10 @@ static void LoadDefaultBg(void)
 {
     if (IsContest())
         LoadContestBgAfterMoveAnim();
+    #if B_TERRAIN_BG_CHANGE == TRUE
     else if (gFieldStatuses & STATUS_TERRAIN_ANY)
         DrawTerrainTypeBattleBackground();
+    #endif
     else
         DrawMainBattleBackground();
 }