I find it hard to believe.When goku fights zamasu he goes ssj2 and his power inceases several times over.SSj3 is even greater than that and we all know that SSjgssj>>>ssj3
This would imply that Ssjgssj goku is >>>>>>>>>>>>>>>SsjG goku which is impossible
i do seem to recall Omega telling goku and vegeta that even if they fuse (second time) they wont be able to beat him because they have lost too much power
can he tank the following attacks:
1.Kamehameha from ssjblue goku
2.final flash from blue vegeta
3.rose black kamehameha
4.Sabaki no yaiba
5.Seinaru Gekirin
6.Final kamehameha
Toei could have made pretty decent and memorable work out of this.They could have had goku use the Kaioken during the beam struggle and made it glorious moment.Would have been much better than what we got.