I don't reckon there should be any new types, it would mess with everybody's mind too much and give more plot flaws to the game and anime. On the other hand a divine type would be cool, it's not super effective against anything and nothing is super effective against it, this way it doesn't change the weaknesses and super effective cycle. And with gen4 games not being able to battle with gen5 games, they could change pokemon like arceus to this type.