From Bulbapedia, the community-driven Pokémon encyclopedia.
This is a list of Pokémon in the order dictated by the National Pokédex, meaning that Pokémon from the Kanto region will appear first, followed by those from Johto, Hoenn, Sinnoh, Unova, Kalos, and Alola. Each region's set of Pokémon starts with its own set of starter Pokémon and their evolutions, going in order of Grass, Fire, Water; the only exception is Unova, which begins with Victini, who is then followed by the starter Pokémon.
The first 151 entries in this Pokédex also serve as Kanto's regional Pokédex. In Generation II, this Pokédex order was known as the "Old Pokédex", with a new order that put related Pokémon near each other also included.
List of Pokémon by National Pokédex number