Do you remember back in Generation 4 when Arceus became a Pokémon? There it is, the creator deity of the universe, and the most powerful of all Pokémon! An incredible 720 Base Stat Total, making it (at least by one simplistic measure) the most powerful Pokémon of all. It's a record that was held through Generations 4 and 5 until it was surpassed by Mega Mewtwo and then a few other ultra-powerful Pokémon as well, making Arceus less and less special by comparison. The trait of having the highest Base Stat Total makes a Pokémon somewhat inherently special, but what Pokémon deserves the title? As we draw nearer to Sinnoh being revisited, do you hope Arceus will regain its position at the top with some kind of rebalance or new forme? Should Mewtwo be kept at the top for the Gen 1 honors? Should an entirely new Pokémon sit atop the heavens?
Arceus is basically the Pokémon version of 'God'. Mewtwo may have been the original strongest Pokémon, but that doesn't mean that it has to stay that way. It makes more sense for Arceus to have that honor, because it fits the lore. I wouldn't mind if a new strongest Pokémon gets introduced, as long as the lore provides a good reason as to why they would be the strongest.
I hate it when people say Arceus is the "God" of Pokémon. It isn't. It's the first Pokémon. That doesn't mean it can't be surpassed by evolution or other means. I wouldn't say there's a blanket "strongest mon", ever, for that reason.
I say that Arceus is the 'god' Pokémon because it is said to have shaped the universe, creating everything. This doesn't mean that it has to be the strongest Pokémon, but it explains why it could be. If we're going to have a single Pokémon that is objectively stronger than any others, then I want a good explanation in the lore as to why. Mewtwo has a good explanation, but I personally think that Arceus has a better one.
I see Arceus as the “god” Pokémon more than Mewtwo because of the way you obtain it (by playing the Azure Flute, stairs appear that lead to the Hall of Origin; meanwhile Mewtwo is usually obtained by going in a cave), and its signature move literally being called Judgment (Mewtwo’s is Psystrike, which is just a glorified Psyshock). While Mega Mewtwo has a higher base stat total than Arceus (780 as opposed to 720), it’s because it’s a Mega, which *temporarily* grants it +100 to bast stat total. Arceus’s base stat total is higher than regular Mewtwo’s. Spoiler: Sword and Shield spoiler especially considering the removal of Megas. The Pokédex entries for Arceus state that it was born from an egg before anything else, and that it shaped the world, whereas the Pokédex entries for Mewtwo state that it is the most savage of Pokémon, and that it was created by science. It is for these reasons that I see Arceus as the “god” of Pokémon, which would only make sense as to why it would be the strongest Pokémon.
Personality I consider Arceus completely omnipotent and that the ones you can get through events and the like are weaker avatars that Arceus sometimes bestows upon mortals that gain it's favor.
Competitive-wise, M-Rayquaza is the strongest. At least before Galar. Arceus being the "God" is a very common theory, but that would make a lot of plot holes in most of the movies if it were truly omnipotent. I doubt it actually is. Bidoof is stronger than all of them
Obviously, the answer is Magikarp. Anyone who says otherwise is wrong and should rethink their life choices.
Arceus basically deserves that spot because it's essentially god. And in-game, the most powerful Pokémon has to go to Mega Rayquaza hands down (By the time of this post anyway).
I think that Arceus deserves the spot of strongest Pokémon. I tend to look at Pokémon's base stats, and their innate abilities to be separate altogether. For example, Dialga would use Iron Claw and do damage, but that doesn't take into account Dialga's abilities to literally control time. I look at Arceus and see that the games don't touch on a lot of his otherworldy abilities that in cannon, would make him the strongest. I'm have a feeling that Arceus lost his powers of creation somewhere along the lines considering various factors, but if he still has them, I would rank him as strongest.
Gonna have to still say Arceus. He is the creator of all things, has the highest BST of all Pokémon without the need of other forms, and per it's ability it could be any and every type it wants to be. Not to mention some spinoffs games for sure say he's a god. Pokémon Conquest for instance.