Rhydon is traditionally credited as the first Pokémon designed.
The claim comes from comments and development history associated with Game Freak’s early work on Pokémon. Rhydon’s design appeared very early in the project and was used in game-development material before the public knew the full roster.
Rhydon is a Ground/Rock-type Pokémon introduced in Generation I. It evolves from Rhyhorn and can later evolve into Rhyperior, which was added in Generation IV. Its horn, armored body, and powerful physique reflect the early monster-design style of the original games.
This fact is sometimes confused with the first Pokémon in Pokédex order, Bulbasaur, or the Pokémon most associated with the franchise, Pikachu. “First designed” refers to development history, not numerical Pokédex position, release order, or mascot status. Because the development process involved sketches and revisions, the claim is best understood as the traditional historical attribution rather than a formal in-game ranking.