In our raid, i'm not sure what the other side did but our side was made up of:
me(prot warr), disc priest, enh shaman, frost mage and a boomkin. All you need is 2 boss boxes, 5 medium and 7 small
We started on the Mantid side and the boxes we opened was:
2 panda, 2 medium
2 medium 4 small
1 medium 2 small
1 boss, 1 small
For the Mogu side i'm having a hard time remembering exactly but i think it was something like:
2 panda, 1 medium, 1 small
and then we kept chain pulling a medium with a couple of small ones
1 boss to end.
Sorry i couldn't remember exactly but hopefully it gives you some indication of what's required
put atleast 1 ranged in each group, swap the mage with the rogue. You have to kill the stone statues and you don't want melee wasting their time running all over the place, it isn't fair to have 3 ranged and 3 melee split up into separate groups
You need to alternate the order in groups to kill a boss when the others kill small/medium : Tank the boss middle and cleave sparks.
Our order on mantides : boss => small/medium => boss and mogus : small/medium => boss (when they kill their boss) => boss => small/medium
For your comp, mix melees and ranged is the best choice :-)
My group just downed him this last Thursday. I was on the Mogu side first. Our strat for the Mogu then Mantid side was buff boxes on both first and sub 20% health on those open a big box. After the buffs die, grab them and open some small boxes on the mogu side or a medium on the mantid side. If an urn pops up (either medium or small) stop opening boxes and kill it ASAP. Same goes with the amber-encased kunchongs. After the first big dies on each side we just clear a mixture of meds and smalls until we get to 36... uh... whatever the bar system thing is called... and open the last big one since he gives 14. Usually we have all our cds up by then and it's simply a race to the end.
2 larges, all mediums, 4 smalls. I just openth e 2 pandas, take the corner large and go around the room.
Have a melee in each group for some interrupts on the stone statues, caster mogu mob. And have a mage/shaman in each group for dispelling residue. You can tank the large mobs in the middle to cleave sparks or the stone statues they spawn, mostly useful on the mogu side.
One thing that bothers me on this fight is the RNG between which buff you get, at least on 10 man. The healer one is so far ahead of the other two that it's not even funny. The DPS and Tank ones seem to average around 15-20m damage total per room, but the healer one can do up to 40m. Not only that, but it allows the tank and DPS to ignore the sparks completely. That's a massive disparity, considering how tight this fight is on the timer for those progressing on it.
Sorry for rant. We killed it yesterday but it just seemed so much easier whenever we healers got our buffs.