NidoranM is atype Pokemon introduced in Generation I. it is also known as the 'Poison Pin' Pokemon.
How To Obtain
There isn't actually a Pokemon called "NidoranM" In the actual Pokemon games. Both Nidorans' names are just Nidoran, but they use different sprites and have different evolutions. They are called "NidoranM" and "NidoranF" in-game so that the game can distinguish between them.