Andross
Andross, from the original Star Fox, will appear, move back behind the action, and begin firing polygonal panels at the combatants.
Barbara
She comes from Daigasso! Band Brothers. When she plays her guitar, the soundwaves hit your opponents.
Devil
From the game Devil World of NES (never released in USA) comes the Devil. He will choose a direction and point, forcing the screen to scroll in the same direction.
Dr. Wright
This character from the SNES version of SimCity blows away your enemies with skyscrapers that appear from the ground.
Exitebike
Many motocross racers in pixel art come out to rush over your enemies.
Gray Fox
Frank Jaeger, the Gray Fox, comes from the Metal Gear series to slice your opponents in pieces. He can also reflect projectiles.
Hammer Bro
The Hammer Bro, originally from Super Mario Bros. will chuck hammers at opposing players.
Helirin
Helirin comes from Kuru Kuru Kururin. It becomes part of the stage when you use it.
Isaac
Isaac from Golden Sun series appears and uses the attack force which appears as a giant hand that tries to push the enemies off the stage.
Jeff
Jeff uses a Multi-Bottle Rocket 5, a device that launches four mini-rockets and one mega-rocket.
Fat Jill & Drill Dozer
Fat Jill uses her drill to drill your opponents.
Kat & Ana
The Katana twins come slicing your opponents while making a dance in perfect symmetry.
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.
Lakitu and Spinies
Lakitu (Super Mario Bros.) comes over its cloud tossing Spinies one at a time. They are in pixel art.
Little Mac
Little Mac comes from Punch Out!!. He is small in size, but strong in heart. Don't take him too lightly because he dashes, throws 2 powerful jabs and finishes with an uppercut that will surely take a lot of damage.
Lyn
Lyndis from Fire Emblem crouches and waits, then vanishes before unleashing a powerful strike at a foe.
Metroid
This little creatures hold an enemy's head and start draining their health.
Mr. Resetti
Mr. Resetti from Animal Crossing burrows up from underground and lectures the players.
Nintendogs
First appearing in the E3 2006 video (long before Assist Trophies were actually revealed), a Labrador puppy from Nintendogs jumps up and blocks the screen.
Ray
This custom robo flies around the stage, shooting energy blasts at opponents.
Saki Amamiya
He comes from Sin and Punishment: Successor of the Earth, with his Cannon Sword ready to slice and shoot against your enemies.
Samurai Goroh
Samurai Goroh, from F-Zero, will slash his sword wildly while chasing after opponents.
Shadow the Hedgehog
Shadow uses the Chaos Control to slow the speed of every enemy.
Stafy
Stafy comes from the game Densetsu No Stafy (Japan-only). He shines bright and does a spin attack. But this is one weak assist trophy because you can attack him.
Tanks & Infantry
Many little soldiers and tanks will march on the stage firing against your opponents and chasing them.
Tingle
He "decorates" the stage with all sorts of effects at random.
Waluigi
Waluigi chases any foe, stomps him to burry him in the ground, then he keeps stomping to finish with a powerful kick or a hit with his racket.