https://onelastforum.com/threads/pokemon-power-scaling-is-literal-fan-fiction.3754/
https://vsbattles.fandom.com/wiki/Arceus
Everyone (every continuity scales to eachother according to Vsbw) would scale to Low 1-C with Infinite Speed using the Logic that a bunch of 3rd stage (Under Marcus) and 2nd stage (Togetic, Pikachu) were able to reach and harm Avatar Arceus, even worse by game mechanics where Pokemon like Lv.100 Pichu are able to inflict damage to Avatar Arceus
Ash physically downscales too because he scales albeit weaker to the Black Belts which trains with their Pokemon
Yu-Gi-Oh Manga continuity on the other hand has apparently Dark Yugi/Atem stopping a universe level attack on his own in the Darkside of Dimensions but i haven't watched it so i can't confirm
There are Obelisk and Orycalcos Serpent which can get Infinite attack, Timaeus and Horakhty can get beyond that but that's on the 2-C range according to the Vsbw which they also say 1-A Spirit Arceus is far beyond anything on the Yugioh verse