Fought a zQGJ, zYoda, Anakin, GK, zBariss team on last stage of GW yesterday.
It was impossible to beat. The foresight at the beginning, the foresight added by zYoda. Finally get GK hurt and then Anakin AoE for stupid damage, usually taking out one of mine (so add foresight to entire other team again). Then Bariss equalize and start all over again on GK, til he's hurt again and Anakin repeats. I know there are squads to beat this, but I don't have one.
Seem pretty viable (though I get it includes a 7* GK which not everyone has access to)