>>40136333Mythicals are just rare Pokémon. They aren’t beasts that control a certain category or element that makes up the laws and features of the universe. They are just unique Pokémon that can do cooler things than regular Pokémon. And if you paid attention, you’d notice Mythicals commonly aren’t bound by the same design philosophies and rules as Legendaries.
For instance, for many Mythicals, there’s more than just one of them, while with Legendaries there is only one and the only real reason we can catch multiples of regular Legendaries is because of space time fuckery.
Arceus is a Mythical specifically because its God, and can’t be grouped in with its lower creations, while also not having a category of its own.