Edit: TIL Set Bonuses do not work in CM. Apparently only Ret is viable in CM. (Thank you Mr. Streamer)
I could tell you that :P gems doesn't work either :)
Hpala works aswell afaik. The streamer you saw is mostly looking from a boosting point of view where you carry a noob.
so the best setup for that is
Tank = DK (OP)
Healer = Druid (Best burst dmg of all healers, not the best healer tho for cm)
DPS = Heavy aoe (Shaman, combat rogue)
DPS = Nice single + aoe (example arms warrior)
DPS = Pure single (example destro lock)
This is one of the best setups, not the best. but all have their benefits from different classes.
I have talked a lot with a CM booster who is streaming aswell :P he was the one giving me that spreadsheet.