I think a lot of characters from old games should be included, not just Nintendo ones:
Mega Man - if they put Pit in there, they should definitely bring in Mega Man for the next installment of the series. He has a lot of potential and could be one of the better characters.
Crash Bandicoot - He also has a lot of potential and is a good addition to the series, I think. But Sony probably wouldn't let him be in the game because it wouldn't be on that console.
Spryo the Dragon - Pretty much the same as Crash.
Tails - the more the merrier. Would appease Sonic fans, and seems like a pretty cool character.
Knuckles - same as Tails.
Walugi - No reason not to put him in there, I think most people surprised not to see him in Brawl.
Toad - He should be his own character, not just one of Peach's moves.
Koopa Troopa - Maybe. Since he was in Mario Kart Wii, it might be okay to be in an SSB game, but since it's just a minion, not a main character, I'm not sure.
King Boo - Possibly the coolest character in existence. Should be put into the next SSB game no matter what. He's just so cool! Right?
Bomberman - Maybe. Not as well known as some others, but still a kind-of classic character.
Just my thoughts on new characters.
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[email protected]His Royal Highness Utterly Awesome CoW I, who rules over the City of Wonder, posted the last message of 2009 and is now known as Mootilator.