Spydr Enzo
Smash Ace
I'd say that the Donkey Kong series is actually overdue on some representation. King K. Rool is considered a shoe-in by many, due to his significance and his popularity, and Dixie Kong is pretty popular as well. She probably wouldn't be a basic model-swap of Diddy, similar to Melee clones, if she is even a clone at all. Plus, her ponytail alone gives her a pretty big amount of abilities that are unique to Diddy (Ponytail Helicopter recovery, grabbing things and attacking, etc.). The Donkey Kong series is no doubt deserving of two new characters...
Wario suffers from the same problems that plague the Yoshi series, and therefore will probably not receive newcomers any time soon. Others have already mentioned this.
Wario suffers from the same problems that plague the Yoshi series, and therefore will probably not receive newcomers any time soon. Others have already mentioned this.