I'm sure he gets a lot of sun running through the city with Doc beside him on a bicycle.
You could do local multiplayer as a split-screen time attack to see who can beat a fighter the fastest.
For online multiplayer, they really need to include a create-a-fighter mode that allows you to make some hilarious creations. I would structure a system that would let you register in a weight division, and then have a regional ladder system that allowed you to fight three or four people for a lower belt, fight three more and win a belt, fight three more and win the championship. Like a regional tournament, and then once you win the championship you can fight whoever you want, or enter world tournaments.