Genie would make a great character, using his magic. Then again so would Jafar, his special move would be hypnotising his enemies like he did with the sultan and Iago and Abu (monkey) would make good team ups with Rajah as a mount!
Aurora or Snow White could call upon the forest creatures like Mickey's special or sing as their ranged attack (if it was snow white then that would do more damage ) Pocahontas use leaves (the colours of the wind) and her special would be kinda like Gamora's. Mushu's special move would be like Iron Fist's and he would be able to fly and when attacks he says "Dishonour on you! Dishonour on your cow!"
Dipper and Mabel would be great characters, with a Waddles mount and Bill Cipher would be awesome. Simba and other lion king characters would be good, but only Timon and Rafiki would get in if they don't have quads.
Prince Eric could use his flute and Ursula could be like Maleficent, and have a costume disc to Vanessa, or when she's on land she could, same with Ariel and if she comes, Melody. Flounder and Sebastian would make good team up discs and so would Flotsam and Jetsam, that said, they could be part of Ursula's special move. Scuttle could be a flying mount (talk about it later) and Eric's ship would be a cool vehicle. An Atlantis or Eric's Castle building set would make it all tie together
Belle could throw books, Beast could roar and Gaston would use a pop-gun , Lumiere would make a good team-up disc where he could sings enemies with his candles and Belle should be in her normal blue attire with a costume disc to turn her into her yellow dress
Flying mounts would be a good addition to Infinity, Pegasus and Dumbo and Scuttle come to mind, the idea is that instead of sprinting (hold L2/ LT) they fly!