IMO, Magimaster was supposed to be this game’s Super Hard Boss, but unfortunately they forgot to make him immune to berserk… If not hem, then the Brachiosaur would be the hardest battle in the game, even if not technically a “boss” battle. I mean seriously, IT CAN CAST ULTIMA!!!!!!

Really though, there is no one in this game on the level of Omega and Shinryu in FFV. You can always make bosses super hard though, by casting haste etc on them.