SKmarioman said:
What I'm looking forward to this are palette swaps that are considered to be actual freaking palette swaps and not separate characters that take up the roster.
Considering that you just select whatever color you wish for the 8 Yoshis and Shy Guys in the Mario Kart 8 DLC, I think the best option would be for characters like Metal Mario and Cat Peach to be alternate costumes for Mario and Peach respectively instead of compromising slots that could be going to Boo, Dry Bones, Diddy Kong & Bowser Jr. Koopalings are pretty unique from one another though so I don't think they would work as "alternate costumes".