I'd suggest (these are what I usually do) one of two things.

Make everyone Bare. Equip Ribbons, Angel Rings, and the other best equipment. Combine your mastered abilities to be effective.

Or

Make everyone Mime. Mime Fuuma Shurikens.

Or, in your case, cast Shell (or Big Guard if you have it.) on everyone when you fight X-Death's first form, as it'll carry over to the Neo fight. (Cuts down on Almagest and his other spells.) Use Golem to intercept physical attacks. (Reapply as necessary.) Your levels are perfectly acceptable for the end-game. I'd really suggest at least putting a Mime in there or something, and maybe someone with Throw. If you can't do that, then I suppose Bahamut/Jumping/Holy is a good offensive tactic.

I don't see any reason to beat them in a certain order, the last part will always go berserk with Meteor anyway.