From the trailer I see that the characters from Alladin, Hercules, Beauty and the Beast and even Mulan.

In Agrabah, it would seem that you run into Goofy's rival, the big guy who isn't really ever an important role in very many Disney things.

I've seen pictures of Auron, and he's in the trailer too, I've only heard rumors of Yuna and Vincent. And it makes sense that Leon, Yuffie, Aerith, Cloud and Cid will all return.