Do you guys think I should do these bonus bosses for my project (allies vs. bosses)? Why or why not? Personally, Kurt Zisa may be possible with enough patience, but I'm not sure about Phantom. Donald would definitely be in the party, and I guess it'd just be a matter of waiting for him to cast the correct spell. (In the first game, he's very smart regarding what spells to use against enemies, such as only Gravity or Stop against the wizards since they're immune to everything else, but I'm not sure if it works the same way with Phantom.) Discuss.
Definitely both. Phantom was a fun fight because of it requires you to change your mindset from that of solely combat. Kurt Zisa is just a good fight in general that tests all of your timing and preparation skills, kinda like Sephiroth.
If he casts the right magic, he can, the same way physical attacks from him, Goofy, and Peter Pan can damage the Phantom when it has the white sphere.
I know the white sphere bit, and normally I'd ask for proof... but it's you. I think you're a good source here.