Seymor fleux is a very technical battle in the sense you need an awesome straegy to beat him but a dierct quote from the offical FFX guide "Even with all these pointers there is still a certain element of luck to surviving this battle" he took me about 2 tries I beat snactuary keeper no problem on my first try(it might have something to do with the fact that my bahamut could mega flare for 22347 damage at that point SK's full HP- 40,000 so yeah over half of it's max HP)I overkilled it with my dragon king's mega flare Yunalesca..hmm I think I beat to her second form on my first try my second try yieled me to her third form..my 7th try to finally beat her(she kpet using mega-death to kill all but one of my characters then follow it up with a full life totally made me throw my control on the floor and smash my brother's drums for an hour and half as hard as I could, and all I can say is thank the gods for sound proof rooms)