BFTD beat (I think it was him) FFx-2 twice in one day, and he hates it so he probably took breaks as he played... incredibly easy game (someone some day should do a challenge, maybe straight white mage party with no accessories or something)

FFX had a few bosses that could pose a challenge. People have had trouble (including me) with bosses like the third Seymour or Yunalesca the first time through. I tried not to use aeons much, and so never used an aeon sac strategy. I also always healed zombie against Yunalesca because it's a negative status effect and got pummeled by mega death a few times, then I beat her without trouble, but still it took me a little while.