8 characters huh? All right, lets see...
1) Ridley: A very good possibility, and I'd love to see him pwn Kirby
2) Black Shadow: F-Zero needs another representitave, it was one of the original series in smash.
3) King K. Rool: say what you will, he'd be a great character. And DK needs a bad guy!
4) Issac: I haven't actually played Golden Sun, but this character seems more and more likely.
5) Skull Kid: You all know he'd be awesome...
6) Geno: This guy is EXTREMELY popular and wanted, and Square Enix being in the credits for brawl heightens his chances
7) Krystal/Wolf: I personally think starfox has enough reps (Dark Samus PLEASE!!!) but it seems highly likely one of these two will be joining the roster, so in they go.
8) Banjo Kazooie: Perhaps the most fit character for brawl. Although his chances are pitiful, I'd be ecstatic to see him.