After thinking about it for a bit, i actually think the best squad to use against Traya doesn't include all bounty hunters. I think a Jango Fett lead with Qi'ra, Enfys Nest, Boba Fett and Greedo would be the best counter. The turn order you want is:
1st: Enfys Nest (more easy to go first now with the +30 speed boost and open with AOE daze and TM removal)
2nd: Qi'ra (apply Stagger to everyone with her AOE special)
3rd: Jango Fett (aoe with burning + -25% max health for hitting a debuffed person + triggers contract)
4th: Boba Fett (aoe ability block + triggers Jango's contract)
5th: Greedo (remove buffs andTM and stun and give everyone else crit chance up)
by this point you have reduced a lot of TM on their team and you are almost done with the contract. Enfy's Nest was already one of the fastest characters and with the extra +30 speed, she's even faster! AOE with daze prevents counter attacks and TM gain plus the 20% TM removal chance is really good. Qi'ra putting stagger on people reduces their TM to zero once Jango hits them with his aoe.
and are you maybe thinking how are these debuffs going to all be applied? Qi'ra has a really sneaky good unique ability and when combo'd with Jango's lead its devestating: Qi'ra gains +40% potency against enemies without a debuff and shares half that with other scoundrels. That with -40% tenacity from jango's lead makes the enemies have a low chance of resisting the Daze from Enfys and TM removal. if they are debuffed, Qi'ras unique gives bonus to crit damage.