I ended up doing this, and I also had had Tidus cast Hastega so he didn't even get a turn in before he was dead. There's got to be a good way to beat him without just overdriving through it. I guess I'll check yt.
I did it like so:
0. Make sure everyone has something with Zombie Ward equipped (not ABSOLUTELY necessary, but it helps).
1. Start with Tidus, Lulu, and Wakka up front.
2. Have Lulu cast Bio (he's actually vulnerable to poison, helps a lot).
3. Have Tidus cast Hastega on team.
4. Spam Silence Buster every time Wakka's turn comes up (to keep him from casting Flare, Reflect, and Dispel on your Hasted team).
5. Start beating the shit out of him.
If you want, switch out Lulu for Auron after she casts Bio, and Haste him up too.
With this strategy, I got the job done in a couple minutes. Not a single summon was used.