Mew Year

When it all began, there was very little life. There were only two beings in existence. Both had come to be at the same time. Why they came into existence? That is still a mystery. These two beings were Arceus and Mew. The two were both the first to come into existence. Where there was nothing, they became something. And with their existence came more life.
Arceus was the first to do an act of creation. With its unlimited power came the universe. As a result of this massive creation, two eggs came to be. They hatched into two slightly lesser beings, Dialga and Palkia, the beings of time and space. From the eggshells of those beings came three more, Uxie, Mesprite and Azelf, the beings of knowledge, emotion and willpower. Arceus continued to bring into existence more and more creations, including planets, stars and air, making it so there was no longer emptiness in the universe.
However, Arceus’s mass creating had adverse effects. The energy exerted by the creations of these objects was too much, and in order to control it Arceus created a second, much smaller universe called the Distortion World. In there it stored the strange energy to prevent it from halting the creations being made. But, as more and more was created, the energy became too much for even the other realm to contain. Arceus became panicked with this, and called upon Mew, who had done nothing during it’s time of existence. Arceus told Mew to find a solution to the problem at hand.
After giving the situation some thought, Mew came up with a solution. Going around to the few other beings in creation, it figured out how to make a life. Taking Arceus’s power to make the universe grow, Mew created a third Pokémon to rule by Dialga and Palkia, Giratina, the ruler of the Distortion World. Mew gave specific orders to Giratina, telling him to only use his power to control the distortion world. Giratina obeyed, and went into the Distortion World to control the leaking energy.
Arceus was very happy with Mew’s accomplishment. In honor of that, Arceus asked Mew to create more new creatures to populate his creations. Mew complied, but it took a full year before it could create a new creature. When it did, Mew created Kyogre, the ruler of the sea. This being made the oceans on the planet Arceus specified, current day Earth. A year later, however, Arceus called on Mew again. It requested another being to keep Kyogre from making the Earth all oceans. Mew agreed, and hurriedly created Groudon, ruler of land. Groudon created the lands of the Earth, in order to counteract Kyogre’s kingdom. More time passed, and the disagreements between Kyogre and Groudon reached a breaking point. They began warring, trying to prove who was better. Arceus told Mew to once again create a new ruler, this one being able to control the two rulers of the Earth. Mew created Rayquaza, king of the sky. The gigantic green dragon settled the feud by making Kyogre and Groudon fall into a long slumber, after which falling asleep himself.
Arceus continued asking mew for more beings to fill his creations. Mew complied, but it took longer and longer for the little creature to make more creatures. It eventually got to the point where Mew took a full year to come up with a new Pokémon. Arceus just kept demanding more and more to be created, stressing the poor pink cat. Over a long time, mew had created the rest of the legendary Pokémon that were to roam and rule part of the Earth. By the time the legendary dragon Pokémon that would eventually split into Reshiram, Zekrom and Kyurem was created, Mew had been worn out. The small, pink creature confronted Arceus with the problem. Arceus was furious that Mew thought it had done enough creating. Arceus wanted the Earth to be full of different life, and until the world was packed with beings, Mew was not allowed to stop. Mew was outraged at this. They argued for years, nothing getting done at all in the universe.
Finally realizing that they needed to come to an agreement, Mew proposed a solution. Every year, Mew would create a new species of Pokémon. Instead of only creating one of each, however, Mew would create many of that one species, allowing the world to populate faster. Arceus agreed to the idea, albeit a little reluctantly. And so it was settled. Every year, mew would create a new species of Pokémon until the world was entirely filled with them.
And so, as the years went by, more and more Pokémon species come into existence. Arceus knew Mew would fill up the Earth quickly at this rate, however, and sometimes killed off an entire species without Mew noticing. Arceus would blame their disappearance on extinction, and turned the bodies into fossils to be dug up later. Many centuries later, Mew came up with another species that both Arceus and the pink cat agreed they loved, humans. They decided to give them knowledge, but not nearly as much as the legendaries. Yes, humans are technically Pokémon.
And so, this process went on for a long time, and is still continuing today. At exactly the start every new year, Mew creates a new species of Pokémon. And that, my friend, is why we call the start of every year, Mew Year.