I have a quick problem
I think it's too much assumption to assume the gogeta in base doesn't scale to their strongest forms "aka sane and ssbkk20"
The fusion ins base is => the strongest forms of the people who make up the fusion.
Because if base gogeta was weaker than ssbe and ssbkk20 goku and vegeta, they wouldve transformed into them.
But the fact that they immediately ruined away and thought about fusion, which is something they only use when it's absolutely necessary, goku had to remind vegeta what would happen if they don't fuse everytime in canon.
So fusion for them is the last resort, because it goes against Thier own fighting style and vegeta's pride. Because if the fusion wasn't the last resort they wouldve transformed into ssbkk20 and ssbe to try their luck against broly, but they didn't, they immediately thought of running away instead of facing him like they did against multiple opponents.
Halftime 2-C = toppo. Kefla, ssbe and ssbkk20 goku and vegeta, supressed jiren.
2-C = Mui goku, full power jiren. "Possibly ikari broly?" Base gogeta, ssj gogeta and ssj broly, lssj brolly and ssb gogeta.
"In the anime, goku preformed much better in ssb than he did in UI, so wouldn't this mean ssbkk20, and ssbe would have rating of possible 2-C?"