I don't know if this is right... So correct me if I'm wrong :3

A. Level 3 Key Sphere
Usage- unlocks level 3 lock
Steal- Biran Ronso (Mt. Gagazet)
- Yenke Ronso (Mt. Gagazet)
S. Rare- Ultima Buster (Monster Arena)
Drop- Lady Yunalesca (Yevon Dome)
- Sin's Right Fin (Airship)
- Sin (Airship)
- Seymour Omnis (End of the Sea of Sorrow)
- Ultima Weapon (Omega Ruins)
D. Rare- Defender Z (Yevon Dome, Omega Ruins)
- Behemoth King (Inside Sin)
- Demonolith (Inside Sin, Omega Ruins)
- Machea (Omega Ruins)
Bribe- Demonolith (Inside Sin, Omega Ruins)

Q. Free Question.