List of generation I Pokémon

The first generation (generation I) of the Pokémon franchise features the original 151 fictional species of monsters introduced to the core video game series in the 1996 Game Boy games Pocket Monsters Red, Green and Blue (known as Pokémon Red, Green and Blue outside of Japan). Later, Pokémon Yellow and Blue were released in Japan.

Source: Wikipedia — List of generation I Pokémon (CC BY-SA 4.0)