I'd list all my SMBA characters, but I'm sure that's not what you had in mind.
I suppose I can list all the various partners/characters I've considered for my Paper Mario X ideas. These have all been cut from my recent plannings, except as maybe some humorous cameo.
Squeena: A Li'l Mouser with a bonnet. She had the ability to persuade other characters to give information or key items to Mario. She got dropped because I decided the Goomba could do that anyway.
Klepton: A Bandit in a trenchcoat. He had the ability to pick certain locks that impeded the game's progress. Kinda useless overall, when all you need to do is add an extra key.
Oreyeon: A Mr. I with a feathered headband and a medicine pouch (lawsuit for Indian referencing). He could see in the dark. He was really only there to replace Watt, and got replaced by a Fireball move.
Bigga: A Buzzy Beetle with Magikoopa glasses. He had this dilemma thing about choosing to go to Kolorado's School of Archaeology or Kammy's School of Magicks. He was a Kooper replacement, and was substituted for a Koopa Troopa.
Chelsea: A Chain Chomp with a funky hairdo. She could ram into walls and cracked objects to break them. Basically a Bombette replacement, and was replaced by a Bob-omb.
Poe D. Boo: A Lava Bubble who looked kinda like a gypsy. She could burn stuff and melt ice. Was replaced by Fireballs in general.
Ditto McCloaker: A Duplighost that could turn Mario (and in early planning, Peach) into nearby enemies. I couldn't get a good look for him, and Masa was jealous because I gave Ditto a reference and not him
, and Guisseppie is cooler anyway.
Bulbette: A fancy Bub-ulb who could throw/plant seeds. I actually made her up after finalizing my partners for Paper Mario X, so she wasn't really replaced.
Mayor Spike: Wario in disguise, the mayor of Crooksville (which was dropped) replaced Koopa Koot as the guy who sent you on crazy errands. Near the end, he was going to have you find Wario's hat and clothes, and then put them on and you'd have to fight him. He's been changed to Mr. Spike (still Wario in disguise), who runs the local division of WarioWare, Inc. in the central area.
Sheriff O'Dove: Waluigi in disguise, he played a significant role during the Crooksville chapter, and didn't really have much planned for him after that. He's been changed to Mr. O'Dove (still Waluigi in disguise), who also runs the local division of WarioWare, Inc.
I'll have to redraw them and/or find some good pictures to put up.