Thank you, that really helped! Now that we're at it, do you have any idea that is there an event command that makes the event change the animation type?
You can use switches. For example:
You have the switch for the boss, BattleGearON! (It's an anime reference, someone here can guess which? XD)
You then create an event with
two pages. The first you set the animation for the boss with his
normal sprite. The second is the boss with the
battle mode sprite, you select the condition
Switch BattleGearON = ON for this page.
After you talked to it, and the boss unlocks his
battle mode, you set the
BattleGearON = ON, and in the second page (available only if BattleGearON is ON), the boss is in his
battle mode sprite.
It's basically the same you do with chests opening, switches activations, etc.