The one that most people use is Chirpatine + tanks.
Chief Chirpa(L) - Gives all your non-ewok allies +5% dmg and +10% TM gain.
Palpatine - Basic attack - Deal dmg to enemy and apply Shock. For each Shocked enemy gain 15% TM. So from here, you shock all the B2's without killing them and then you use basic attack on the Rocket Trooper a lot of times.
The 3 tanks are there to protect your Palps and Chirpa.
Aside from that I've seen maxed out jyn + chaze + another tank + DN. DN uses annihilate on the Rocket Trooper, thus dealing tons of dmg. Jyn is there to revive your rebels and steal TM.