I farmed up a set of mastered Elemental and Added-Effect materia to go Weapon hunting, but it turns out that was unnecessary as long as I could open with Great Gospel and then mime KotR a bunch. I wasn't quite able to beat them without taking any damage, but close enough.
Then I stumbled upon Ozma blindly, and that was quite a surprise. I attempted it a couple of times without Aerith's limit ready and got wrecked pretty hard (being at level 72, 75, and 76 didn't help
), but I think the same idea should work, especially if I farm to level 77 to dodge all the level-based stuff.
Anyway, I unlocked Ozma trying to get Tifa'4 level 4 limit break. I got 1 gil from playing the main theme as Cloud at her home piano and then got Ozma at the Shinra mansion piano. Does she need to be party leader or am I doing something else wrong?