That's what I did. I didn't have Doomsday when I fought Hades, so I didn't have to worry about it. Oddly enough, I spent 15 minutes re-arranging my armor and weapons to fight against Hades' Doomsday as best could, and I killed him before he could use Doomsday. I was really surprised. Level 49 was highest character, on the way to Memoria.

And Ozma... was a pain, stupid Chocobo side-quest.