So yea this is basically a fight against Terra and the whole purpose is for Donald and Goofy not to take any damage.....wow...
The only plausible way is to stock yourself with ethers and spam limits. I also used final form because it looks awesome and it's easy to avoid the DM with it.
Also keep in mind that while Sora is in final form, he mustn't take any damage, since he has Donald and Goofy inside of him in some way.
Enjoy the most pointless challenge of all times!!!
![](https://s2.save4k.ru/pic/qj3jQ61S4YM/mqdefault.jpg)