After several hours of real pain (mostly due to watching the bloody cut scene over and over...), I finally beat T5 with:
Boba (L) G12 + Zeta
IG-88 G11 + full Omega, no zeta
Dengar G10 and one missing Omega (B&S), no zeta
Greedo G10 + full Omega, no zeta
Bane G10 + full Omega, no zeta
MoDs: LV15, mostly blue, quite bad.
Forget about your PVP MODs, you cannot match their speed ! (save your $)
Focus on killing Chewy first (NO AOE !). Once he's dead, it gets much easier. Do not use Greedo Special to remove Buffs or you won't kill him with execution. Keep it for R2 or Lando before they throw flames or AoE.
Then I killed Lando, Leia, Solo (and finally completed my contract...) and R2 last.
The key is having Dengar stealthed after their first attack so R2 can't stealth them and wastes a turn.
MVP Dengar (Unic & Basic) and Bane (Basic)
Last man standing (barely) was Dengar (thanks to R2 being an **** and trying to stealth all teh time...). Honorary mention to Geedo who attacked 6 times in a raw and dispatched HS without getting punished by a counter...