Suggested by Mehama Sadafa this is definitely a really close battle. After all by the end of their evolutions you’re basically debating Mirage Gaogamon Burst Mode and Omnimon in his final Tri form. Both of these guys are some of the strongest Digimon out there. I would have to give Mirage the edge here though. He’s shown much better speed feats over the years and part of the problem for Omnimon is that he outranks everyone so severely that typically you don’t really get to see what he can do. What ends up happening is that the fight is over before it truly begins. I do think it would be a pretty epic fight though. Gaomon wins.
Gaomon has a whole lot of super forms so he won’t go down here very easily. That being said, I think Vegeta is definitely the character with the edge here. His super strength and speed are off the charts and he seems to get stronger and stronger with every arc. Gaomon is out of luck here because his physical stats just aren’t quite good enough to match up to Vegeta’s. It’s like a cub taking on a lion. Vegeta wins.
Suggested by Mehama Sadafa Pikachu is one of the strongest Pokemon out there, but that series does eventually hit a ceiling. It may be a high one, but it’s there nonetheless and there are Digimon which have broken through that. Gaomon is one of those. While Pikachu would be able to take Gaomon in his rookie and champion forms, his ultimate and perfect modes get a little tricky. Then you’ve got Burst Mode and it’s all out the window for Pikachu by that point. His speed is simply not enough to keep up and at that level even his famous Volt Tackle likely won’t make much of a dent. It’s over for him now. Gaomon wins.