The account I play on my computer managed to unlock chewie using the classic Bossk, Boba, Dengar, Bane, Greedo team. They were modded for potency of course under a Boba lead to allow most to survive the initial onslaught.
Total potency was just over 210% so nothing crazy, but sure did allow for a buffer to the damage.
Nobody over G9, total GP just under 50K.
Account was level 81, just turned 82. (was planning on putting a zeta on bossk if I hadn't unlocked him by then)
Before changing some mods on a couple for more potency, I was struggling. After doing that and getting the potency up I had no trouble. I near completed the first attempt but retreated out to see just how lucky I was. Got to where I would have won(several BH left with just Lando or R2) 7 times before finally finishing it off. I would say about 15-20% were victories.
Of note: Make sure Bossk goes first(or at least before Boba) so he taunts then Fett executes Chewie with all the buffs. Bossk can then finish chewie or use net on Solo if Chewie is gone.
Would like to see others report if they were able to use a lower powered squad to complete the unlock.