It's bad game design, but melee really do make Garuda X a lot more difficult than it has to be. I've only beaten it once at this point (though I've watched and read a ton of guides and practiced quite a bit before my win), but the best method seems to be having the MT pulls Garuda and Suparna, OT pulls Chirada. All DPS focus Suparna and then switch to Chirada.
Benefits:
1. The tanks only ever have to worry about provoking spiny. Currently, with the more popular method of killing Chirada first, if spiny lands on the MT, the OT will have to provoke the spiny once Chirada is dead and the MT will have to eat a second DWW. If Suparna is focused and killed first, the MT only has to worry about one DWW and the OT only has to worry about Chirada's downburst, which will never one shot him. Plus, with Suparna dying quickly, the MT won't have to dance around as many times avoiding double Slipstreams. Another advantage to this method is no teleport or feather rain thanks to Suparna dying before Chirada.
All in all, everything's easier. The MT only has one huge burst he has to CD up for each twister phase and provoking is always saved for the spiny plume alone. Plus you get to avoid mechanics like Feather Rain all together.
I suppose you could still do this method with one Melee DPS on Chirada as long as your ranged DPS was strong enough to three man down Suparna off the MT quickly.
The method I used in my first kill was all ranged, but I OT Suparna instead of Chirada. In the circle phase, I would provoke spiny first and keep it away from the group. In the twister phase, the MT grabbed Garuda, Chirada and spiney first and I took Suparna. The DPS killed Suparna off of me first, and I would then provoke the spiney off the MT. DPS switches to Chirada and kills her (MT would have to provoke spiny back near the end). This method is a lot more on the MT, having to hold two adds the whole time, but since there are no Wicked Wheels once Suparna dies, all he had to really worry about was eatting a single Wheel + Chirada's downburst and then when Suparna was dead, just the Chirada downburst. So, the damage he took wasn't too bad after Suparna was dead. But again, in this method, a Melee DPS would have had to dodge Suparna's WW and the range is so huge, it's very risky even if the tank tries to get Suparna into a corner (and sometimes, she simply doesn't want to move with you once the tornado's spawn). A Dragoon would be a little easier, since the can Elusive jump during Friction and then Spineshatter/dragonfire (depending on where the spiny is) back in.