6,000,000,000 years ago
At the beginning of the universe, there was one Pokemon. Arceus, the Pokemon god. The first Pokemon he created was Mew, the ancestor of all Pokemon. Arceus copied Mew’s DNA and injected some of it into his three first creations, who became Dialga, Palkia, and Giratina. Contented that he had created Pokemon to shape the new planet, Arceus gave them orders and retreated to his dimension.
Mew injected his DNA into his creations, Ho-oh, Lugia, and Raquaza. All Pokemon forevermore would have Mew’s DNA in them. Ho-oh created the beasts Suicune, Raikou, and Entei. Lugia created the birds Zapdos, Moltres, and Ho-oh. Raquaza created Groudon and Kyogre. Dialga and Palkia crafted time and space for the new world. Mew, Arceus, Dialga, Palkia, Giratina, Lugia, Ho-oh, and Raquaza would forever be known as the Eight Guardians.
Dialga created Celebi for mundane tasks of time travel. Groudon and Kyogre created land and sea to move around on. Palkia created Jirachi to grant wishes and Deoxys to govern one of the new continents. Giratina created Cresselia and Darkrai to balance light and darkness in the universe. Raquaza was uneasy about the fact that the continents were being swept around by the sea.
Raquaza created Regigigas, who created Regirock, Regice, and Registeel. The three Regis built Sky Pillar, Tin Tower, and Brass Tower respectively. Regigigas towed the continents into place, but a huge chunk of land broke off and formed the Whirl Islands. Then, Raquaza retreated to Sky Pillar, Lugia to Brass Tower, and Ho-oh to Tin Tower.
The three beasts were placed in the Brass Tower and the three birds hid in places on the continent called Kanto.
Now, Mew created the Magma Stone to regulate Earth’s heat. Mew created Heatran to protect the Magma Stone and confined the two to a volcano in the continent Sinnoh.
By now, Groudon and Kyogre had become rivals in expanding the land and sea respectively. The two started fighting a war against each other so they could further their own goals. Mew supported Groudon, as he thought more land would be fun to play in. Mew started mass producing regular Pokemon to defeat Kyogre. The sheer amount of Pokemon overtook Kyogre for a while. The world’s heat became unbearable and the temperature made a furnace look like the present-day Sinnoh.
Jirachi and Deoxys, fearful of Groudon’s growing power and the threat he posed to their own safety, decided to take matters into their own hands. Deoxys started mass-producing regular Pokemon to fight for Kyogre. Jirachi started granting them wishes so they could overtake Groudon.
These events had been enough to draw the attention of Arceus, who reapearred on Earth. He sent Giratina to capture Mew, Jirachi, and Deoxys and Arceus called a council of the Guardians.
All eight Guardians attended, as well as Jirachi and Deoxys. Giratina, in capturing the three Pokemon, maimed them horribly. Arceus, horrified, banished Giratina to the Distortion World for his violence. Arceus banished Deoxys into the far reaches of the universe, away from Earth. Also, Arceus used his power to send Jirachi into a deep slumber, and cursed him to only wake up once every thousand years and only be able to grant three wishes each time. As for Mew, Arceus banished him to a remote island called Faraway Island.
Now, Arceus had to deal with more pressing matters. He created an army of regular Pokemon, woke up the slumbering legendaries, and they went to war. Now there were three sides: Groudon’s, Kyogre’s, and Arceus’s.
The war continued for a thousand years at a stalemate. Eventually, Arceus used an incredibly powerful Judgement, which sealed away all the legendaries, at the cost of most of Arceus’s power. The remains of the energy created a race called humans. Arceus was horrified at his creation of humans, and stated that a thousand years in the future, he would choose a human to destroy all other humans, as he was too energy-drained to do it himself.
Mew stated he would choose another human to combat the human Arceus chose, as Mew simply was physically incapable of leaving the island until his six billion year exile was over.