I've been listening to a lot of videogame music today, so I started thinking about what tracks I'd like to see in Brawl...For starters:
~ Wario Ware: Smooth Moves
Final "Boss" Theme - Put this in with a crazy, randomizing Wario Ware stage and it'd be the best stage ever!
~ Star Wolf's Theme - I'd personally want this thrown into that Arwing Battle stage that I'm hoping for, but the theme is so epic that it needs to be in the game regardless!
~ Sami's Theme/Super Power Theme (Advance Wars) - Because I really, REALLY want Sami (and the awesome soundtrack) to get into the game...
~ Aerie Fortress (Jungle Beat) - Because it's the best theme from the game (and a rocking battle track too!)...
~ Pollyanna w/ vocals (Mother) - Anyone else have the Mother Vocal OST? Such a great song...

~ Dragon Roost Island (Wind Waker)
~ Dark World Theme (Link to the Past) - I can't believe this didn't make it into the last game...Seriously...
~ Venus Lighthouse (Golden Sun) - Aha, never happening, but... ;_;Into potential 3rd party territory:
~ Final Fantasy character - Classic FF battle theme
~ Sonic - Green Hill Zone or Lava Reef Zone
~ Tales character - Fighting of the Spirit - There's seriously like a 0.000000001% chance of a Tales character making it into the game, but this is the best battle theme in any RPG ever... ;_;
Okay, I better not get too carried away...