>>249781701. It's confirm by the Pokédex.
Arceus come from a Egg. Arceus created a Universe. You know there's more than one right?
2. Mew could have came from a Pre-existing Parallel Universe.
3. multiverse (or meta-universe) is the a series of finite or infinite possible universes, including the universe we live in. Together, these universes comprise everything that exists: the entirety of space, time, matter, energy, and the physical laws and constants that describe them.