Vargas - first few times I played the game, I didn't pay attention and figure out his blitzes. In fact, the first time I beat Vargas with a blitz was an accident: I was trying fighter game move combos - left, right, left, A. For some reason, I've still yet to find where they tell you the blitz before you get Sabin. lulz.

Ifrit / Shiva - I've always been under leveled or improperly equipped for these fights (everyone using flame sabers gooooooo). A fun fight, but when ifrit unloads on you, it can be painful.

Favorite Boss - Ultros:
the comic relief was really well received by me. I enjoyed facing him in the fights we had.