My top picks would be:
Bolt (Using his actual movie magic superpowers is possible. Stuff gets altered when heroes make it to the city. (Buzz makes a comment about how his laser actually isnt just a lightbulb)
Kuzco, Pacha, and Kronk (and possibly Yzma if her poisons work well) from The Emperor’s New Groove.
Mushu: As I see it, It would actually be quite easy to make him into a hero. He has a good background and importance in his story.
Lightning McQueen and Mater. a tow cable could be used to good extent and provide an alternative to Woody.
Syndrome: Zero Point energy would have many uses and the Omnidroid could even be summoned.
Chicken Little. This thread isnt about the plausibility of possible characters, its about characters users want to see. And I want to see chicken little. Soda Pop jetpacks could be interesting. As well as his baseball “skills”.
Tarzan. I see possible problems arising from his choice of clothes, but that would be it in terms of obstacles stopping him from joining.