I recently tried this fight on my BST. I failed, but I failed because of my own stupid mistakes, not because it wasn't possible; it's very possible. My mistake was not realising his regular attacks have a small AoE range, or at the very least cone-AoE. I got hit because I tried to melee with my pet and then, on his second form, his draw-in + Damage/Terror TP move killed me. I need to try again but you have to complete ALL the fecking mini-games again -.-
My advice is to use Falcorr, don't melee, and sub something that isn't NIN or DNC that can heal you in some way. /SCH would be good for this fight if you have it since the moogle takes 4x magical damage, and 1 Drain/Aspir can bring you back to full HP/MP (or so I've read). Bring a couple of mulsum if you feel like a backup is needed but Reward alone should be fine.
As far as the fight goes, if you can survive his draw in + pwnage, you're pretty much set. It does heavy damage (like 900-ish to me) and inflicts terror for ~10 seconds. You'll kill him to 75% and he will use it, so make sure that you're @ 100% HP when he's about to get to that. When you get him to 50% he will go away and recover HP, and summon some mage moogles which have hate on whoever had hate on the main moogle. Falcorr can take the spell spam no problem and I never actually rewarded him while he killed them all, and kill them all he did. You can help kill them as long as you run when you see an AoE being cast and you're careful about their TP moves.
When he rejoins the battle, and he will rejoin when he's @100% HP (sometimes sooner) and is invulnerable until you kill all the mini-moogles. He then repeats the same pattern. When you take off 25% of his life he'll draw you in and rape you with Crystalline Flare, and when you've taken 50% of he'll retreat, heal, and summon his buddies. If you make it this far you've pretty much won. On his third and final form he will never draw you in, so stick your pet on him, get out of range of Crystalline Flare and that should be the end of things.
Get your HP to 100% before his Crystalline Flare and this fight shouldn't pose much of a problem.
Edit: One more thing! Pull him to the entrance at the start of each phase (I didn't do this... another reason for my failure) and then let your pet do all the work. The only thing that will kill you this way is his draw-in + Crystalline Flare, and if you die at the entrance you can RR without aggro, with the added bonus that he never regains HP.
As far as I'm concerned gear is irrelevant for this fight since meleeing is what will get you killed. Monster Gloves +2 would be helpful but I doubt they're necessary; they're soloable, though!
Edited, Feb 14th 2013 12:02pm by Diamondis
See You Space Cowboy