i dont know if anybody has said this yet, but the hardest rpg boss was that stupid secret sphere monster in ff9...this guy was made to be the hardest boss(by squaresoft at least). he had spells that would kill your whole party in one hit, even at lvl 99! i forget what he was called, but i know for a fact he is the hardest boss in the final fantasy series(because he was made to be the hardest). few have beaten him