Pokémon Red and Green Versions/Features/Pokémon

Each game contains pre-recorded data on 151 different species of Pokémon, including, a Pokémon even Nintendo was not aware of initially. However, not all Pokémon are available to the player, regardless of version; trades must occur between players in order to complete their Pokédex without the use of cheats or glitches. In addition, Mew is not normally obtainable in either game; the only legitimate way to obtain Mew is through a Nintendo sponsored event.