Vegeta clearly doesn't think much of Gohan and Dabura, saying Gohan shouldn't be having this much trouble and that he will step in and end the fight. Even though he probably said that to push Babidi's attention towards him and, therefore, get mind controlled, this goes uncontradicted, so no reason to discard it.
I have Vegeta's gap on Dabura similar to the gap he had on Dodoria, to which I think it's enough to give him the win against these two (who are pushing 80~83% of him), though this wouldn't be easy, even more with Dabura's usage of magic.