Here's how it's done:

1. All characters Lv. 99 with maximum stats (255)
2. All weapons, armlets, accessories, and items
3. All Lv. 4 Limits learned (including Aerith's)
4. All WEAPONS beaten
5. Six Gold Chocobos, all S rank
6. Nine of each Materia, all mastered, one for each character. That includes the Master Materias (Magic, Summon, Command)
7. Learned all the Enemy Skills on all four Enemy Skill Materias
8. A lot of Gil (about 360,980,542)
9. And all that in 27 hrs 30 mins