Here are ideas for several characters I like to see in the New Smash Bros. game (Even if they don't come true):

Sonic the Hedgehog, Banjo-Kazooie, Kat and Ann (From Warioware Series), Cloud from FF7, Leon from FF8, Sora from Kingdom Hearts series, Donald and Goofy (Kingdom Hearts versions), Mickey Mouse (Kingdom Hearts 2 Version), Riku from Kingdom Hearts series, Knuckles, Shadow the Hedgehog, Darth Vader.

This is only the few ideas I remember, do you have your own ideas?