Because there are so many things to farm, I have to go with the toons I have next time:
Boba (Lead): 7*/G12/Zeta
Dengar: 7*/G12/Full Omega
Greedo: 7*/G12/Full Omega
Cad Bane: 7*/G12/Full Omega
IG-88: 7*/G12/Full Omega
All have 5*/Lv15 MoDs with Potency (+65% to 99% per toon) except Greedo who has ~99% Crit Chance (he nearly finished Chewy all by himself on his first turn when I played T5)
My IG-88 is almost G12 and all (except CB) should have their Zeta by the time the event comes back (assuming it's not coming back until February, 5 month...)
My weakest link is 88 but I hope I won't have to rely on RNG too much with that squad.
How long after the first time doe a Legendary event usually comes back ? I'll have the 3 Zetas by end of December but I hope I can use them somewhere else