Here are a few good ones:
Emerald Weapon

Game: Final Fantasy VII (US Release)
Emeral Weapon was one of two bonus bosses added in the US Release o f Final Fantasy VII. It's sister boss, Ruby Weapon, was certainly no pushover, but Emerald Weapon is consistantly rated as the harder of the two due to its immense amount of HP, and it's ability to take up to 9 turns in a row, not to mention the unblockable super move which can kill all party members Aire Tam Storm.
View a battle (at 2x Speed) here
Ozma

Game: Final Fantasy IX
Ozma is a hidden boss in the Chocobo Air Garden. To get this far requires diligence in the Chocobo Hot & Cold minigame, but to challenge seekers, it's a rewarding fight. Ozma absorbs most elements, making some usually heavy hitters such as Vivi completely useless. It uses an all-attacking skill which deals shadow damage to everyone (but heals Ozma itself) called Doomsday. It's deceptively normal HP amount is very hard to whittle away at as it heals itself almost as often as it attacks.
Tip: Apparently if you complete the Friendly Monsters sidequest, you will make Ozma weak against shadow damage, meaning Doomsday will damage Ozma!
See Ozma beat in one round here!
More to come!












