Look, let me explain the true beginning history and where Arceus rank as:
-The Cosmos was just a pitch black void filled with darkness until a giant Egg suddenly appered and Arceus the Creation Pokemon was born from the Egg.
-Arceus then decided to create the Universe and the "Pocket Monsters" World by creating the Ancesssor pokemon known as Mew.
-Mew was given a task as the Ancessor to mold the Universe by giving birth to;
>Dialga (for the creation of time), Palkia (for the creation of Matter and Space), and Giratina (for the creation of the Afterlife).
-But Giratina was angry at Arceus for letting Mew for being the Ancessor and giving him such a useless job of being the Death Lord of the Revurse Realm (Torn World).
-So Giratina planed a Coup-D'Etat against Arceus by trying to kill Mew and then have the authority to command and convince Dialga and Palkia and together overthrow Arceus.
-But Arceus who was watching from the Beginning Demension (Upper Yard) saw through Giratina's plan and punich Giratina for commiting a Sin againt the Ancessor Mew and itself "the Original Being", by sealing Giratina in the Torn World and resizeing the Realm into the later created Turnback Cave.
-Mew had heard of the Sin Giratina commited and decided to form the Beings of Emotion, Knowledge and Willpower.
-The three Beings now known as Azelf, Mespirt, and Uxie did their job by doning the Red Chain, the bedrock of the balance of the Universe and if this chain is to break then the utter destuction of the Universe shall Comence.
-After the plan was fulliled, Arceus left Mew to continue to mold the Universe while it fell into a deep sleep only to be awakened again by the Chosen One who dons the Azure Flute.
Thats what happends in the true beginning history of Pokemon, from what I read at the Canalave Libary books in Pokemon Diamond I based the story from above to these books.
As for the rest of the Pokemon history toword the fulture, it gets too complitcatedand long so I'm not gonna explain.
I hope this clears things here.
Bass DX:)
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