Yeah, you can win with 3 blms too! What were you thinking?!
...In all seriousness, though, this mission is not one that I'd expect most non-manaburn pickup groups to be able to win. If you nin tank it, you have to have a really good whm for erasing his slowga and keeping you cured, and you're still probably going to die when he uses geotic breath, or from one of the times that he terrorizes you. With a paladin, you're going to be taking a ton of damage, but it's probably doable. I don't have any personal experience with it, though.
Personally, the setup I enjoy the most on that fight is with two nins to share tanking, a whm, a dispeller, a blm, and any other random damage class. If I'm doing it just to get some people done with the mission, though, I'm going to do it with 3-4 black mages, a tank, and a dispeller, since that's about the only setup that can reliably kill it without using 2hrs and without a ton of coordination. 4 summoners is supposed to be the easiest way to do it, but you have to 2hr there so you can't do the fight for multiple people back to back.