diddy: Diddy really was the man in all the Donkey Kong Country games. But recently it seems like the little monkey is more annoying then cool. Can't stand the racket he makes in Double Dash. If I saw Diddy in Brawl I would be happy, but if I didn't I am not sure if I would be disappointed. Maybe mildly.
krystal: I never played the new Star Fox games. She could add variety with her staff and magic, but otherwise I don't know too much about her to really want her in. Although personally I think she will make it.
dedede: Yea! I want more villains. A fat floater would be fun. But as long as he is not just a merger of the IC's and Kirby.
ridley: He would be incredible. Ridley VS Bowser fights would be great. Remeniscent of Japanese Monster movies. They already have the "King Kong vs Godzilla" style of Bowser and Dk. Ridley would be like Rodan. Fast ariel giant reptile to Bowser's slow strong tank build.
sonic: People wanted the Mario, Sonic fight since the dawn of time. Or at least 14 years ago.
ballon fighter: I think I would want villains first and maybe some more major characters, but I think the balloon fightersif made right could make such a fantastic cooky fighter.
geno: Eh. I never really liked Geno in the rpg. He was my least favorite character. Could have a bizarre moveset.
megaman: So many potential movesets and a good Samus rival.
wolf: I say Andross, then Falco, then either Kyrstal or Wolf. Wolf is the cooler looking character, but I am afraid his moveset would be too close to Fox's and Falco's (if he returns).
lucas: Looks just like Ness. What gives. Either pick Ness or Lucas, Sakurai.
olimar: Potential for a wacky fighting style. I say sure.
stafy: Looks ... boring. Kirby and Jiggs were just balls and they did have fun movesets, but I just don't see much potential in this star. Some simple designs are alright: like GandW, Kirbs, and Jigs but too much kinda takes the cool factor out of the game.
fawful: Blag. I liked the game he was in, but the guy is annoying.
tom nook: A merchant who uses his goods as weapons? Sounds wacky. I like it although I never played the game.
hector: I hate FE characters. They seem so boring with all their plain slashes. An axe is a cool weapon and Hector seems like the best choice from the series, but I would rather none appear.
skull kid: Never played game, but he looks creepy. The game could use an actual freakishly scary looking representative. Zelda characters are so bizarre, I love it.
kamek: I never thought of this choice. But Yoshi could use his own villain instead of sharing Mario's. I doubt he would be in, but very unpredictable but impressive pick.
hitmonlee or paras: I think four pokemon is a good number. Pichu could be replaced by almost any other non-electric, non-meowth pokemon and I would be happy.
koopa troopa: Not exciting for me. Toad would be a better pick because he was playable in one of Mario's main games.
prince: After reading Dotdotdot's forum and both his and McFox's ideas for the character I would have to say yes.