Pokémon gender was a concept introduced in Pokémon Vortex Version 3. Almost all species of Pokémon were assgined a gender, male or female, but Legendary Pokemon do not have any gender. Gender makes no difference in the stats of a Pokémon, but the gender could affect evolution paths. One such example is 
Nidoran (M) and 
Nidoran (F).
Single-gender Pokémon
Gender-based evolutions
Certain Pokemon have to be a certain gender to evolve.
| Base Form | Item Required | Evolved Form |
 Burmy (Plant) |
 &  Female & Level 20 |
 Wormadam (Plant) |
 Burmy (Sand) |
& Female & Level 20 |
 Wormadam (Sand) |
 Burmy (Steel) |
& Female & Level 20 |
 Wormadam (Steel) |
Burmy (Plant) |
 & Male & Level 20 |
 Mothim |
Burmy (Sand) |
& Male & Level 20 |
Mothim |
Burmy (Steel) |
& Male & Level 20 |
Mothim |
 Combee |
& Female & Level 21 |
 Vespiquen |
 Kirlia |
&  Male & Dawn Stone |
 Gallade |
 Nidoran (F) |
& Female & Level 16 |
 Nidorina |
 Nidoran (M) |
& Male & Level 16 |
 Nidorino |
 Snorunt |
& Female & Dawn Stone |
 Froslass |