Andross
Andross, from the SNES version of Starfox, will appear, move back behind the action, and begin firing polygonal panels at the combatants.
Devil
From the game Devil World of NES (never released in USA) comes Devil. He is one of the assist trophies that do not assist you because he scrolls the screen leaving a tiny piece of land to stand on.
Dr. Wright
This character from the SNES version of SimCity blows away your enemies with skyscrapers that appear from the ground!!!
Hammer Bro
The Hammer Bro, originally from Super Mario Bros. will chuck hammers at opposing players.
Knuckle Joe
Straight out of the Kirby universe, Knuckle Joe comes out with a devastating Vulcan Jab and will end with either a Smash Punch which shoots straight through the enemies or a Rising Break which is a super powerful punch straight down.
Nintendog
One of the images posted on the official Super Smash Bros. Brawl website (Smash Bros. DOJO!!) shows a Labrador puppy from Nintendogs jumping up and blocking the screen, and now we finally know what it is: an Assist Trophy.
Samurai Goroh
Samurai Goroh, from F-Zero, will slash his sword wildly while chasing after opponents.