Let's see
Luigi:
Luigi reaches back, and with a trembling finger... taps the "release" button on the Poltergust 3000. Suddenly, 50 boos stream out of the Poltergust's tank while Luigi screams and cowers in horror. The Boos go on a chaotic rampage across the screen, smacking into all characters but Luigi, and taking a few precious moments to make faces at the screen. Suddenly, Luigi finds his nerve, hits the Boos with his flashlight, and sucks them all back into the tank.
Ganondorf:
Ganondorf grips his hand into a fist, showing the Triforce of Power. The golden triangle's light suffuses his body, and he mutates into Dark Beast Ganon (from TP). The beast form allows Ganon to rampage about the stage, goring anyone in his path (thanks to The Dojo).
Fox:
Fox speaks into his communicator, calling in an air strike. He then activates a Barrier (from Star Fox Assault), and a Nova Bomb (from Star Fox Command) falls onto his position, creating a hemisphere of concussive force that begins to spread about the stage.
Peach:
Tiny sparkles surround Peach, and she raises one hand, summoning the Power Stars of the castle. All 120+ stars fall onto the stage, exploding on impact and dealing a little damage each time.
Samus:
Samus's Power Suit begins to flash white. She jumps into the air and two illusionary Samuses surround her as she flies across the stage, semi-similar to the movement capabilities of the Volt Tackle. She shoulder-bashes anything she hits, and deals good damage and high knockback. The one flaw is that Samus's health deteriorates as she uses this move, so her percentile goes up as she uses it. (100 E-cookies to the first one to guess what that is inspired from)
Donkey Kong:
Donkey produces his trusted Bongos. He then begins to bang a hot beat on them, ending his performance by standing on them and striking a pose. With this, a huge DK symbol in reds and yellows shoots across the stage like a sound-based shock wave , smacking into whomever it can reach. (However, if Diddy is in, he should have this move, except replace "bongos" with "guitar", "bang a hot beat on them" with "rock out", "standing on them" with nothing, and "DK symbol" with "star")
