The two strongest Pokemon in the series finally duke it out! Pikachu is a close second, but I believe that these two would defeat him in a fight. Despite the fact that Deoxys has never been playable in Pokken or Super Smash, he’s really close to Mewtwo here. Before Mega Mode, I’d say that Deoxys very well may have had the edge here. His speed is impressive and his instant regeneration would make an anime villain proud. He has several modes, which really makes him ready for any kind of attack, but Mewtwo’s sheer power should be enough to stop in his tracks. It would be a long drawn out battle, but one where Mewtwo ultimately has the edge. Mewtwo wins.