I've written this for the "brawl is more balanced" thread, but I'll put it here as well
the tops are not leagues over the highs, Marth may be a good all around character, but none of his smashes kill as easily as luigis firepunch combo, or Lucas' Usmash, or Ikes Ftilt, or many other great moves in the game, yes he has comboability, but it can be avoided by forseeing it and airdodging correctly, yes he has edge guarding, but there are many things you can do against it, I see a character where one grab can get you from 0% to(ICs Fair and Popo-Nana combos) KO as much more annoying than a character which has a lot of good things, but none of them are ultimate or unbeatable, they're just good.
the way I see it, brawl has a humongous amount of balanced characters, which are divided into groups of potential, and also has a strong counter-pick sort of metagame, where knowing characters with diffrent styles will really help you out, and playing only your main character will leave you open to a big amount of counter pick downhill matches.
I see brawl as having around 10-12 top tier characters, 10-12 high tier characters,8-10 mid tier characters, and 5-7 low tier characters, which are underbalanced. the ones I'm apting for that category ATM, are gannon,Falcon,Yoshi,DK and maybe one more yet to be decided.
I also feel that mid tiers will have very good chances against tops, because of differing styles,ranges and tactics, and that ultimately a person playing 3 Mid tier characters, will have almost as good a chance of winning as one playing 3 Top tier characters.
also, I'm sure the tier list will get scrambled lots of times, but ATM my predictions for it are(in no particular order):
Top:
Luigi
Marth
Diddy
Meta knight
Pit
Olimar
PT
Zelda
DDD
Toon link
Wolf
High:
Peach
Zamus
Lucas
Ike
R.O.B
Snake
Mario
Wario
GaW
Ice Climbers
Falco
Lucario
Pikachu
Kirby
Mid:
Ness
Bowser
Fox
Sonic
Samus
Link
Shiek
Low:
Falcon
Gannon
Yoshi
DK
Jigglypuff
while Writing I felt diffrently for some character potentials, and ended up with a 11-14-7-5 formation. but that's my current feelings about character potentials.
also, aside from the low tier characters, the diffrence between mid and top is around the diffrence between high and top in melee, and between high and top is half that. that's how balanced this game feels to me.