Spoilers for Fraction and Aaron runs on Thor....
There have been a couple fights. Odin seemed worse off than Galactus in the fight written by Fraction. And under Aaron, Galactus fought and defeated King Thor (who had the odinpower longer than Odin had it).
The Fraction fight did not even have Galactus throw a punch. Odin downed himself with his own headbutt. That was such a poorly executed battle in most respects.
One could say though that Galactus was already battling Asgard on his own minus Surfer. Odin had his army and Galactus had PC constructs to battle them.