The first generation introduced 151 Pokémon species.
These original species occupy National Pokédex numbers 001 through 151, beginning with Bulbasaur and ending with Mew. They appeared across the first-generation games, including Pokémon Red, Green, Blue, and Yellow, although obtaining all of them required trading between versions or using special events.
The number 150 can cause confusion because Mew was initially hidden and not normally obtainable through standard gameplay. Mew is still counted as National Pokédex number 151, making 151 the correct total for the original roster.
The first-generation Pokémon came from the fictional Kanto region. Their designs established enduring species such as Pikachu, Charizard, Jigglypuff, and Meowth. Later generations expanded the Pokédex dramatically, but the original 151 remain especially important because they formed the basis for the franchise’s early games, anime, trading cards, merchandise, and worldwide launch.