This is a very difficult team to face, but I've had success maybe a dozen times or so using the following strategy:
You're going to need three GREAT teams, at the very least, and you should preload their TM and reset their cooldowns the first five nodes of GW.
Your first team is high-DPS. Droids or rebels, whichever is faster and stronger. The goal is to remove all protection from all opponents. Don't plan on doing any better than this, if you can remove all protection from all enemies, you're on the path to success.
Your second team is a control team. Stuns and Dispel work well for me. I use an ewok hybrid team... Chirpa lead, EE, Teebo, GS, Daka. You need to get to and kill Zarriss with this second team, retreat if you can't do it. You need somebody to dispel the crazy buffs (and autotaunt) from Kenobi in order to get to Zarriss. Once you kill Zarriss and all the enemies' protection is gone, you can DH ally make progress on the health of the remaining enemy toons.
The third team I use is my arena team, Empire. Palp, Vader, ShT, TFP, B2. Buff Immunity and fast dispelling helps to neutalize Kenobi, kill him next if you can. Once Zarris and Kenobi are gone, the remaining three, whoever they are, shouldn't be a problem.
If you don't have an empire team, I've also had success with both JKA and IGD-lead Jedi as my third clean-up team
I hope this helps! Give it a try and post your results!