Suggested by Sonic Acnologia is one of the most powerful dragons of all time. His abilities are so good that it took multiple dragon slayers to take him down. Dragonite has his hyper beam but Acnologia could crush that with his fist. Dragonite has no realistic options here that would make this fight even close which is why he will end up being completely stomped. That’s before Acnologia even activates his human form. Acnologia wins.