The original Pokémon games featured 151 Pokémon species.
Pokémon Red and Green introduced the first generation of Pokémon, numbered from Bulbasaur at 001 to Mew at 151 in the National Pokédex. The games’ main regional Pokédex covered the creatures encountered in Kanto, while Mew was a secret Mythical Pokémon that was not normally obtainable through ordinary gameplay.
Players were encouraged to catch, evolve, trade, and battle Pokémon. Because Red and Green contained version-exclusive species, completing the collection required trading with another player or using additional games. This collecting structure became one of the franchise’s defining features.
A common mix-up is counting only the 150 Pokémon normally listed in the original game data and forgetting Mew. Later generations expanded the Pokédex with new species, but forms, regional variants, and special transformations are not always counted as separate species. The 151 figure specifically refers to the first generation.