What we have here Is two great warriors who surpassed villains who were based on the devil.
Let me tell you something about this guy, he has all the abilities of the most powerful Digimon In Season 4 combined including the villains, and the further forms, he Is the the Vegito of Digimon making him ranked to the top 5 most powerful digimon out there.
He can even send his enemys to hell sort of, fighting villains who destory planets.
On my honest opinion I do believe he was the most powerful pokemon out therem but only was sense he seperated alot of power for the universe.
Even though that happened he was still able to overpower Girantina,Palkia and Dialga three enemys whom would be on pare with Generation III teams.
Now Its up to you to decide who will win.