If it's: Dormammu with eternity's power and in dark dimension VS Well-fed Galactus with the power of the cosmic force (since the post said at full power), then I would say dormammu, he is able to tank classic strange's magic (which is powerful enough to seal the beyonder) with only a slight scratch. Dormammu is very close, equal, if not > eternity, they have fought countless times with no conclusion and dormammu has now absorbed eternity's power. Even someone with just a FRACTION of dormammu's power STOMPED classic strange. All of these feats and people heavily surpass galactus' feats and who he scales to.
Kaido, med difficulty, Akainu will throw like 10 or so attacks at him and Kaido will be slightly injured then he would just yeet him to the moon with Enel. Kaido is around 1.5x-2x stronger than him. However, later on in the series Akainu will become a final villan and be MAYBE yonko level.
Well his devil fruit might be stronger, but Kizaru has trained his more and Fujitora cannot create black holes otherwise he would be 5x stronger than everybody in the galaxy combined. Doffy was not scared to fight Fujitora btw.