I loved the movie, but seriously, it's not an action-like movie. It's a comedy. Kuzco (or however u spell it), would be a terrible party member. He's a LLAMA! XD And Izma would jsut be a terrible boss, period. And yeah, I jsut don't think it would fit BBS, or any KH for that matter :\
BUT, on the other hand, they did make Chicken Little a summon... XD lmao. So I guess anyting's possible...