All the first Pokémon (more context in comments)

Mew - Game lore, Mew was the genetic ancestor of all modern pokemon, it was the “first” pokemon

Rhydon - purported to be the first pokemon designed by the game designers. It is the “first” pokemon actually created

Bulbasaur - In the Pokedex, in number order, Bulbasaur is pokemon 001. Bulbasaur is the “first” pokemon.

Arceus - Game Lore, Arceus is the literal God of Creation, Arceus was is and ever shall be, Arceus is the beginning and the end the alpha and the omega, Arceus created the world, but it’s still a pokemon (and you can catch it). Since Arceus existed before the world, Arceus is the “first” pokemon.

Yup, that checks out

Yea that is everything we need to know

To be fair, Diglett was made waaay before Pokemon was even a thing, when the developer was a kid he drew that very thing

Or Rowlet

Cuz in PLA ur making the first ever Pokédex and Rowlet is the first in said Pokédex.

Lol

Diglett:

whoops

sorry

Digglet: