Have you seen this (https://www.youtube.com/watch?v=DVO8QrGAPHs) Battle Royale of Legendary Pokemon yet? If not, congrats! Now you have!
Anyway, the question is: Which Legendary Pokemon do you think would most likely win in a Battle Royale scenario where Pokedex Entries are assumed to be true (i.e. do you agree with the video), and also in a scenario where they aren’t true (because the Pokedex really doesn’t seem like a reliable source of information) and you’re just using their in-game combat capabilities?
…I think I might love this
But yeah, to answer the question… well, I don’t think I need to agree with the video for it to be great, because it’s supposed to be funny and not, like, a watertight argument for a position in a “who would win” debate. But let’s talk about it anyway.
If we believe all the myths literally… well, Arceus in that case is God, so I think pretty obviously it wins, which is one of the two outcomes the video offers. I also agree, though, with the assessment that if any Pokémon can challenge Arceus, it’s Ultra Necrozma. If Arceus created the universe, then it presumably has some kind of power over everything in it. Your best bet to overcome Arceus has to be something from outside the universe. So far we’ve seen, I think, two things that qualify: Giratina (who seems to be subservient to Arceus) and arguably the Ultra Beasts, of whom the greatest is Necrozma. Now, I don’t think anything we’ve seen Necrozma do, or any feat attributed to it in mythology, holds a candle to the creation of the universe. It brought light to Alola in ancient times, it was injured by the burgeoning technology of Ultra Megalopolis, it devoured all the light of that world, it consumes the light of Solgaleo or Lunala to regain its own former powers, it has frikkin’ laser beams… sure. In the video it devours the sun to empower itself, and honestly I kinda buy that as something the mythological Necrozma could totally do, but even then, Arceus created gajillions of suns. I’m not even sure we’ve seen anything that makes me believe, on the strength of lore alone, that Necrozma could beat Dialga or Palkia (Dialga is the heartbeat of time itself; the fact that you were even born in the first place means it’s already going easy on you). But because it’s arguably outside the creation of Arceus, it’s a wildcard, and kinda gives us more latitude to make stuff up. The alternative is a video where Arceus just steamrolls everything, which would be boring and predictable – so I disagree with it as an assessment of Necrozma’s strength and abilities as expressed in the lore, but I absolutely agree with it as a creative decision, which is much more important.
There is… I think probably one point in the video that I take serious issue with, which is Yveltal killing everything on earth after Necrozma zaps it. That’s based on the Pokédex entry that says “when its life comes to an end, it absorbs the life energy of every living thing and turns into a cocoon once more,” which… yeah, okay, but that can’t mean “every living thing” on the entire planet, because… well, how could the Pokédex possibly know that? If it had ever actually happened, there would be no one left to write the Pokédex. I think it makes more sense to read that as “every living thing in the area” or perhaps as “some of the life energy of every living thing” (i.e. old and weak organisms die all over the world, maybe others get sick, history might remember the event as a terrible plague, but life does basically go on). Even putting all that aside, I don’t think we ever saw Xerneas get taken out, and Xerneas ought to be a force of life equal and opposite to Yveltal – doesn’t it get to attempt some kind of counterplay here? I get that doing this with Yveltal is a convenient way to dispose of all the “leftover” Pokémon and, y’know, animation is hard and time-consuming, so I can’t blame them for not wanting to show every last legendary Pokémon bite the dust, and make a joke of every single one, but still… it’s the one thing about the video that feels kinda lazy to me.
Depending on exactly how you model the fight and define the rules, I actually think Arceus may still win even if we use only the in-game abilities of the Pokémon to settle things, purely because Arceus can just change its type between fights and always have a super-effective Judgement against whatever it needs to beat next. Plenty of legendary Pokémon can take on one or more of Arceus’ forms, but it’s damn near impossible to be ready for all of them. There’s a couple of other Pokémon that might still give it a run for its money though, just on sheer stat absurdity alone – Mega Mewtwo Y and Ultra Necrozma are faster, and you might be able to nuke it with Mewtwo’s Focus Blast if it shows up as a Dark-type, or Necrozma’s Light That Burns the Sky if it doesn’t. Lugia might be able to outlast it with Recover and Multiscale, actually, but I don’t think Lugia is a strong choice to win the whole thing.