Just remove the commented out function and notes.

src/battle_controllers.c

@@ -62,20 +62,6 @@ void SetUpBattleVarsAndBirchZigzagoon(void)
     ClearBattleMonForms();
     BattleAI_SetupItems();
 	BattleAI_SetupFlags();
-    // this isn't necessary, and is dangerous
-    // if we just finished a double battle
-    // as this function modifies array elements
-    // by using gActiveBattler as the index
-    // and gActiveBattler isn't reset upon
-    // entering a battle
-
-    // this bug affects vanilla as well, but vanilla
-    // does not perform any array element writes
-    // and any garbage values due to the result of
-    // reading an invalid array element are reset
-    // when the AI chooses its move
-
-    // BattleAI_SetupAIData(0xF);
 
     if (gBattleTypeFlags & BATTLE_TYPE_FIRST_BATTLE)
     {