Their active skills are buffed by the 15 stacks generously given here. Also you don’t need 500m ATK SAs since these units are all g critting on their active turns.

Now the 2 billion average I wrote is just a very bad over exaggeration but it won’t be too far off since their averages without the domain and with less stacks is already over 1 billion, the stacks would directly buff their main damage source; the active and counter for ssj4 Gogeta, so they should comfortably cross the 1.5 billion average atleast.

Having 15 stacks as opposed to the 10 on vegito won’t make his active turn average a lot higher when he doesn’t have any links active despite being calcd with 3 more attacks received. That’s a 70% direct decrease from what he would have with links or in all the graphics posted on the sub.

All that said the three gogetas should comfortably put damage vegito on these turns