Strategy: Ashoka and c3po help a lot here. You need to have gear parity between Gk and GG at the very mininum. Depending on many factors, this fight can go either way. Everyone should be g13.
As C3po is g12 for most ppl, and if B2 inflicts buff immunity on Gk before you get the chance to dispel it and they focus c3po, you will lose. The whole point is for you to control the battlefield, and try to take down B2 while holding protection up and be ready for GG’s aoe.
The base fight (at high relics, but assuning a G12 c3po) GK, Anakin, Padme (in rare situations) or B1 goes first. If B1 goes first he’ll just aoe everyone. Gk/anakin will be forced to hit Magna/ B1(if he’s visible). This flow will trigger B2’s bonus turn, which will aoe dispel protection up. At this point, best outcome is for Padme to come in, cleanse while ashoka dispels magna for taunt and which with a bit of luck doesn’t trigger B2’s aoe dispel.
You go for B2 at this point, kill him off while keeping protection up. C3po will need to conduse either B2, or Magna, depending on the moment he comes into the fight.
After this happens, you’ll just have to drag the fight either until you have a lot of courage stacks and can one shoot GG, or by killing enemies one by one by keeping protection up. Special note to Gg teams with Wat, that will force Magna as a tank. As he can also resurrect seppies,it will force a different kill order, making it much harder. Magna – Wat – B2… Time in which GG can eat you alive