I haven't dualboxed one but I was with a fairly competent rogue in 2v2 for awhile...we got obliterated most of the time. Boomkin heals're too slow(and if you don't heal you'll lose even more, arena's full of perf-spec full pvp abuse any trick possible bastards) and neither of you are sturdy whatsoever; roots is a joke, cyclone doesn't always work(TRINKETLOL) assuming you're not 1shotted by a pompyro fire mage before you even get to do anything. Boomkins just don't have arena viability with no real cc no interrupts and all our "power" being in spells that take so long to cast you'll be dead before they're done in an arena environment.

My advice: MS Warr + Resto Shaman or Holy/prot Pala = invincible. MS = tons of dmg + plate defense, resto shaman = infini-healz that're too fast to interrupt + totems to catch silence spells, pala = enemies focus on you, warr tears them to shreds and you bubble just before death; they focus on warr, you'll simply outheal the dmg.