They may have the speed advantage, but that shouldn't matter much if they don't have the raw power or hax to take out their opponents.
In Decode, Vitium was destroying the Digital World, and begun destroying the Real World as well. Eventually, it would've affected other worlds as well (somewhat similar to ZeedMille from the XW manga). So multiversal within time, and Yggdrasill sent out Death-X-mon to destroy it. It took Taiga (the player), Omegamon X (likely the same one from X-Evolution), and likely others to take out Death-X-mon (this part is not on Youtube sadly). Death-X-mon is like the counterpart of Alphamon, so they should be around the same level. Alphamon has shown to be superior in some cases.
Later on, you fight an upgraded Yggdrasill 7D6 avatar, which is stronger than anything in the game, including Death-X-mon and Lucemon SM (was going to destroy all worlds). It took Taiga (the player) and Alphamon to take it out. Alphamon from Decode might be the same one from Cyber Sleuth and even X-Evolution. This kinda helps his multiversal status in Cyber Sleuth.
In Cyber Sleuth, Alphamon (along with some others) took on the Mother Eater, which can affect an infinite multiverse. Alphamon played a big role in that as well.
Last time I checked, the only "potential" multiversal character in DBS is Zeno (and we don't know for sure yet either), and he can only affect 12 universes. Alphamon is far above any DBS character (including Zeno) in terms of raw power and he also has hax, including the ability to exist outside of the normal flow of space-time. They wouldn't be able to touch him, and even if they could, they lack the firepower to take him down. I see the Digimon winning in R1 and R5. Currently Imperialdramon PM is mostly hype, although he definitely has potential.