*o* Yes I have.
As with many RPGs, the easy way to win is to have very high levels/stats and use that "unfair" advantage to wipe the floor with your enemies. So with higher stats, the less trouble you'll have. But if you're like me, you're seeking a challenge, and maybe you also want to get the rewards of the Colosseum as early as possible (it opens right after completing Latheon Gorge, i think). Again, it's ridiculousy difficult at low levels (65?), and I can only speak of what I've experimented with.
As usual, people like having Raine in their party, for obvious reasons. If you think she can take care of herself, then great. But the problem I had with her is you're often outnumbered, and enemies will gang up on her, and since she's blocking or simply getting killed she's too busy to do anything useful, like healing (there's an EX Combo that solves this problem tho), forcing you to become her bodyguard. That's a waste of my energy.
So at lvl65, it was basically impossible for me to beat it having Raine. Instead, I chose 3 fighters, Sheena, Regal, and Zelos. Zelos has decent healing skills, Regal also has limited healing, and Sheena can use Purgatory Seal like a weak but faster version of Ressurrection. Plus, Sheena has nice summons, and they can all fight. Using Sheena, I run around and weaken all the enemies, while the other two Scatter and work on enemies separately. I also make sure to prevent magic enemies from casting spells, so I'm switching targets often. Changing the party Strategy to fit the needs of each match does help. Have some good food available for some nice home cooking between fights. And I think some kind of Poison prevention is helpful in one of the matches; at least, for my Sheena.