The Story of Arceus.

In the beginning, there was nothing. And then Arceus showed up and said "This place is freaking boring, I'm going to go make some Pokémon."

"So he made Mew, the mother of all Pokémon. And when Arceus was finally finished designing, creating and testing the Mew, he was like, 'This is boring. Mew, you make the other 717 plus alternate forms. I'm going to go play Mario Kart.'"

"But Mew was like, 'How? Don't you need more than one Pokémon to reproduce and stuff?'"

"But Arceus was like, 'Obviously not. I just did.'"

"But then Mew was like, 'Well no duh, you're Arceus!'"

"And Arceus was like, 'Screw you, Mew. Fine, I'll make you another Pokémon so you two can go and do whatever Pokémon do when they're left alone in the Day Care.'"

"Except this time Arceus didn't feel like putting as much effort into making another Pokémon, so he kind of slacked off a little. And what he had was a Pokémon whose sole purpose was to reproduce and troll people in the RU tier, Ditto."

"'Here, Mew, I made you another stupid Pokémon,' Arceus said, throwing the Ditto at him/her/it/whatever with one of his thousand arms that the Pokédex claims Arceus to have, even though it clearly doesn't. 'You can go and do whatever now. I'm going to go play Mario Kart.'"

"And Mew did. And created the vast majority of the 718 Pokémon we know and love (and hate) today. Meanwhile, Arceus just sat around and played Mario Kart at the top of the Spear Pillar and took all the credit."

The end!