I'm glad you didn't go with Ness being Sans. That would've been too predictable.

Okay, let's do this.

Mario: Captain Lou Albano Mario from the Super Show's live-action skits
Donkey Kong: French DKC cartoon
Link: I'm not sure. It almost looks like Nester from the old Nintendo Power magazines dressed up like him
Samus: Pretty sure that's Samus getting bitten on the ass from one of the Super Metroid 4Komas
Dark Samus: Her unstable form from Prime 2's finale
Yoshi: Super Mario World cartoon
Kirby: This nonsense wouldn't be out of place in Kirby's own comic. The same one that had him yelling "Shit!" while escaping a cave Indiana Jones-style
Fox: Muppet form from Nintendo's E3 direct a few years ago
Pikachu: Detective Pikachu beta stuff
Luigi: He's-a fuckin' dead
Ness: Failed PK Teleport sprite
Captain Falcon: Mediocre SNES art?
Jigglypuff: Crappy RB sprite