I think Kefka is the most dissapointing final boss. He's never challenging whether you train or not. There are stronger monsters than Kefka. When I first played through the game, I was looking forward to a good battle at the end. I didn't think I was strong enough to fight him yet, I was just experimenting by going into the tower. Not only did I beat him but he was easy too. That's dissapointment.