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ShineGreymon because Burst Mode is the equivalent of Super Saiyan and he actually fought a good fight against Yggdrasil.

From that list the only one I think that would be remotely fast enough would be Wargreymon. Defensive wise would be probably Gallantmon. But by shear power alone he outclasses the rest. Magnamon and EmperorGreymon are not even close to the strength of a real mega. Also helps that ShineGreymon has defeated more titled Digimon then any of the others.

You got to remember too though that they are all the main character's Digimon so they will have some sort of pride if battles that aren't fair. But let's say that they are just random Digimon without an owner.

Magnamon would get destroyed in seconds.
EmperorGreymon would try to keep up but fail in a matter of seconds.
Gallantmon would go down only cause he lacks flight without granni or crimson mode. If given CM he would definitely be final two.
Wargreymon while fast and strong, his main niche wouldn't help him here. His Dramon Destroyers can kill virtually anyone with "Dra" in their name. Unfortunately no one on the list has that. He also doesn't look like he can take more then a few hits due to his lack of armor and size.
ShineGreymon has kaiju level size and power to back it up. Even outside of hand to hand combat he is equipped with a powerful sword. Then burst mode gives him an additional flame shield too. Making him resistant to fire type attacks leaving his only issue now being Gallantmon's light type attacks. In the past ShineGreymon has defeated many Royal Knights. Assuming all Royal Knights are near equal strength outside of Alpha being the leader and Omni being a close second, I would assume Gallantmon would be in the middle of the Royal Knights as he is one of them. So it's good assumption that fighting him would be no less the same as fighting another Royal Knight.

What if we threw xros in there too? Would Shoutmon x7 imperial super epic max mon beat ShineGreymon(burst)?

Hrm. Then I want that Digimon. blaugh

I think EmperorGreymon would win due to the fact it's a digimon made from 10 over digimon and, in it's own right, one of the most powerful Mega's known. Then if we go to Susanoomon then it would win hands down. Susanoomon is a walking Digimon god.

Equal for the first five minutes then Susanoomon will say something like "ok im bored time to win" and then win. Susanoomon is considered to be beyond a mega. While the same can go for Burst Mode but like I said earlier that its just Super Saiyan. So it would be like a mega 2.0. Susanoomon has surpassed the state of a mega and became a super ultimate. Currently the highest level one can obtain. I think there are only a few Digimon that have made that level.