Which is the first pokemon to have been born or formed or created. Some say it is Archeus. Is it the right answer?
In a vortex of complete chaos and nothingness, a single Egg comes into being, which then hatches into Arceus, the first Pokémon in existence
Also, based on the Pokédex entires from Platinum and Heart Gold & Soul Silver
Platinum: It is said to have emerged from an egg in a place where there was nothing, then shaped the world.
Heart Gold/Soul Silver: According to the legends of Sinnoh, this Pokémon emerged from an egg and shaped all there is in this world.
This information is derived from Sinnoh Myths, which is learned from a Hiker at Oreburgh Mine, and then at Canalave's library in Pokémon Platinum after catching Arceus
But it all starts with Arceus, the first. It is known as the Original One.
"The Original One breathed alone before the universe came."