Tell me more about the cheese method with that team?
Got it off reddit, you can probably find the details easily but here's a summary :
Equip your chizurus with fire weapons, immune status (the worst ones like stone paralyze and sleep, although i'm not sure the boss does sleep) hp gear and dual wield.
Your setzer should have a fire weapon with dual wield and killer materias. He can have low attack. It doesn't matter since he'll be using double dice and it's fixed damage. The killer materias are demon killer, plant killer and a poach or 2 depending on what you use for status immunity (i used discernment). Give him sun barette as well. Mine had around 5k hp I believe.
Ace fire imperils, recovers mana and calls ifrit for the reward.
Rikku needs lots of LB generation items I used Miguel's and pretty much every turn I could use her LB, if not, I would entrust her with ling (you can probably use another unit). When I couldn't get enough lb crystals in 1 round, I would restart the game and try again until I could use it.
Basically you use phantom blade 2x to chain and cap the elemental chain with double dice. It should usually generate enough lb crystals if you have enough lb gear on the rikku.
When the malboro uses devour, close the game and reload it as it won't be devouring again. That way, you never lose a unit for 3 round. Of Rikku is devoured it's over.
Don't forget to dispel the malboro when it's below 50%.
It took me about 45 minutes, but I was clumsy when chaining. I'm sure you can do it much faster. I died on the first round on my first try cause I couldn't get enough lb crystals, but when I figured I could restart the round by exiting, I got the kill on my 2nd try.
Basically, every units you have need to be immune to the nasty effects and the highest hp you can have. I had an average of maybe 5200, so it's not that much, especially with the raid TMs.
Edit : oh yeah and I used diabolo on my setzer and lakshami or something on my entruster for extra heals just to be safe.