To answer the OP - I go with Phasma, Lumi, Rey, Grandma, and 5's - I know Lumi is a jedi... but she does me well, you could replace her with another solid attacker (Asajj isn't too bad these days with her speed increase). Clearly Rey leads my damage, she'll hand over 200k by herself. I always kill the b2, then grandma only attacks the magnaguards and keeps them stunned.
I also run Rebel scum - Lando leading, Han, Leia, and IG-88. The fifth character is sometimes Bariss with her new healness. If you keep the buff-cleaning B2 dead, you could run chewy too, but only if you omega'd his taunt.
Our guildy runs a modified Teebo rancor P1 platoon. Obviously you can't take Grevious TM, but the stealth keeps his and the mangaguards counter attacks at bay. I've run it too, and it either works really well, or falls apart fast. I go with Teebo, Chewy, Tarkin, then whichever attacker I have and a healer if I have left (Often Eeth Koth... a wasted 7 star toon... but he flickers to life a little bit in P1 and p3) . Again, the B2 cleans the stealth, you need to keep him down.