I actually had an idea like that.
>Pokemon Legends Kyurem
>You assemble the Original Dragon
>It's true form is actually a monster on the same level as, if not stronger than the Creation Trio, being an entity assembled from pure boundless energy
>It's Dragon/Normal normally but it's ability allows it to change type with every move it makes
>It's the master of the Genies and the reason why you're time traveled in the first place
>On the other hand, you have a legendary master of the Four Perils
>A thoughtless, heartless beast made from pure nothingness that's based off of Chiyou
>While OG Dragon is limitless potential/energy, this beast is the absolute absence of all. Not necessarily evil, just extremely destructive if it's not under anyone's control
>Typing is Dark/something, maybe Dragon or Fairy or whatever
>Final battle is you with OG Dragon and another Faller with the Chiyou Pokemon duking it out
