About having unique attacks for each character, is this Nintendo going back to its roots? In the SNES version of MK, all of the CPUs had their own unique attak that they would fling at you. Unfortunately, this wasn't included in MK64. I am guessing that is what the person on the back of the cart would be able to do. Bowser throwing fireballs at you, while Peach is driving? Sounds fun to me!
All in all, MK: DD appears to be a blend of features in the SNES version and the N64 version.