Arceus (lat. Assius Maximus World-Creatorius) is a pinnacle of Pokémon butt jokes. The official truth about Arceus is that she's supposed to be the creator of the universe and shit. Well, here's the adult real life truth about good old Arse.
Turns out Arceus, if the religious fanatics have any credibility, created the world in her stomach and defecated it into the Sun. Well, the Sun refused to take any of Arceus' shit seriously and flung it back, missing completely and as a result, the world knocked Pluto into another solar system. This made the first ice age happen.
As the world was flung around the solar system it resided it like a piece of shit, it refused to take any more of Sun's and Arceus' shit and swam through space towards the Sun. As a result, the ice age ended. As it so happens, Red managed to capture Arceus into a pokéball and Sun calmed down. The world cleaned itself from good old Arse's shit and farted out the first dinosaurs.
Thus began the story of a dweeb and ended the story of a legend, Arceus.
Arceus doesn't give a shit about you because she is an arrogant piece of shit herself and it's only natural for shit to create more shit. Arceus liked to say YOLO once every now and then but grew tired of it since she's a goddess and thus eternal, making her a big, fat liar in the process.