I don't recall exactly, but I think it was one of the easiest boss fights I've ever had to fight in FF. I'm pretty sure I made an absolute mess of Zeromus, deemed his abilities unsatisfactory, and never played the game again because it was such a poor game graphically and, definitely, storywise, despite how cool Rydia is.

Where was I? Oh. Right.

This game is a joke, and I think the only times I died were not to the final boss but to the dragons and hardcore enemies of the final dungeon.