Zombie+acolyte is the core of your team.
Everyone extra is just there to do some damage because acolyte doesnt, and also to give the AI other targets for han solo's opening stun and whatever else thrawn and CLS do next.
You could use leia because her damage is good, and nute because he increases their damage. Anyone else you want to use is filler to be honest.
However, i suggest old daka to revive acolyte in case she gets one shotted, and because her stuns are deadly. I also suggest MT because her plague is amazing and she can revive as well. MT is viable at 3 stars. Last, Ventris is most deadly because of her stun and cleanse (which removes turn meter).
My advice is to go with the nightsister route. They are far better than the suggestions I've read above, and they are easy to farm and gear.