Gender
Gender is a feature released in Generation II, first for the Pokémon themselves, and then, in Pokémon Crystal, for the Pokémon trainers. This feature allowed for Pokémon breeding, as well as introduced the concept of a Pokémon egg to the series. Gender makes no difference in the stats of a Pokémon after Generation II, unless the two Pokémon are a different species entirely, such as Nidoran.
Pokémon
Gender also allowed for many Pokémon to have unofficial male and female counterparts, as demonstrated below.
| Male | Female |
|---|---|
 Nidoran♂ |
 Nidoran♀ |
 Nidorino |
 Nidorina |
 Nidoking |
 Nidoqueen |
 Tauros |
 Miltank |
 Volbeat |
 Illumise |
 Latios |
 Latias |
 Gallade |
 Gardevoir* |
 Glalie* |
 Froslass |
 Mothim |
 Wormadam |
| *Can be either gender | |
Gender differences
Generation IV premiered minimal differences in sprite between two Pokémon of the same species. For example, a male Raichu will have the full tail seen in previous games, while the female is missing the very tip of it.
Gender-based evolution
Some Pokémon evolutions can only be obtained if they are of a certain gender:
Trainers
In Pokémon Crystal, players were given the option of choosing their trainer's gender at the start of the game. Since then, every game in the main series has had that choice.
| Game | Male | Female |
|---|---|---|
| FireRed | File:Red.png Red |
 Leaf |
| LeafGreen | ||
| Crystal | File:Gold.gif Gold |
File:Kris.gif Kris |
| Ruby | File:Brendan.png Brendan |
 May |
| Sapphire | ||
| Emerald* | ||
| Diamond | File:Koki.png Lucas |
 Dawn |
| Pearl |
