You can make your redesign as crazy as possible and joking around is definitely encouraged. Or you can make a more subtle redesign.
Personally, I think Street Fighter 5 should be more Hip-Hoppish than the previous games. The menus would have graffiti everywhere and most of the soundtrack would be rap beat versions of the character themes, rather than the electronic stuff they used in SF4. I also think Ryu should have a more urban look. Sounds a little crazy, but it would be cool to have Ryu with a white hoodie rather than a gi and headphones around his neck.