One thing I think would be cool in a future Mario Kart would be if all variants were fixed in to every character - so, everyone has a fire form, everyone has a metal form, everyone has a doctor form, so on.
Not sure how stuff like babies or elephants that couldn't be made into simple skins would be handled with this though.
Not sure how stuff like babies or elephants that couldn't be made into simple skins would be handled with this though.