The Energon Pub

Now this should be interesting, don't post if you haven't read the Galvatron spotlight.

I'm not a great expert on Doomsday but he's in the same power class as Superman so he should beat virtually all Transformers. However, IDW Galvatron has special abilities from the Dead Universe. He may be impossible to kill. If damaged, he heals himself very quickly. Doomsday would have to do something extreme like throw him into the Sun to get rid of him permanently. Doomsday has enough intelligence to work that out and do it fairly promptly. I'd say Doomsday wins, unless he screws up. Galvatron is able to transfer a 'dead essence' to others and thus take control of them, so Doomsday needs to act decisively.