Serebii.net Games - Gender Mechanics

Gender is a concept that originally seemed to only exist with the Nidorans but then expanded in Gold & Silver to be a fairly large dynamic in the games. Almost every Pokémon has a specific gender ratio and the ratio determines how likely it is that you'll get a male Pokémon or a female Pokémon. Some Pokémon have a simple 50/50 ratio while others have a 75/25 and even some as low as 87.5/12.5. Some Pokémon have various differences in appearance based upon their gender
There is only one case of a Pokémon having a different gender ratio as its evolution. Azurill has a 25/75 ratio while Marill has a 50/50 one meaning that one third of female Azurills may change gender to male upon evolution.
In addition to that, there are certain Pokémon which are only male or only female. These are listed below.

Since Generation IV, there have been a few Pokémon who evolved based upon their gender. Sometimes the genders provide an alternate evolution while on others, such as Combee, the Pokémon will only evolve if it is a female..

The more commonly used feature of genders is the Breeding feature. This feature has you put a male and a female Pokémon into the day care centre and breed to get the base form of the female Pokémon. The male parents are the ones used to transfer moves to the Pokémon. For further information, check the Breeding section.

Previously, gender didn't play a part in the capturing of Pokémon. However, there are a few elements which will allow you to manipulate the wild Pokémon of which you will encounter and even increase the chance of capture of the Pokémon.
First, if the Pokémon at the head of your party has the Cute Charm ability, there is a 66% higher chance of you encountering a Pokémon of the opposite gender to your front Pokémon.
Second, in HeartGold & SoulSilver, you have the ability to get the item; the Love Ball. This ball increases the chances of capturing a Pokémon of the opposite gender to your active Pokémon by a factor of 8 making the capture calculation;
CatchValue = ((( 3 * Max HP - 2 * HP ) * ((Catch Rate * 8) * 1 ) / (3 * Max HP) ) * Status Modifier

Attract Status

The Attract status is the main use of genders you shall see in battle. This status is a hidden status like Confusion. It requires the opponent to be of the opposite gender as the user and the user to have a gender

Effects:
The Pokémon afflicted cannot attack 50% of the time

Immunities:
Pokémon with the Oblivious ability
Pokémon of the same gender as the user
Genderless Pokémon (unless used by Mew or Cryogonal)

Methods of Healing
Using the attacks Heal Bell or Aromatherapy
Using the specialised items that follow:

Picture	Name	Effect
	Mental Herb	Removes Infatuation status; can only be used once
	Red Flute	Heals from Infatuation

Methods of Inflicting
If you or the opponent has the Cute Charm ability and the Pokémon attacking that Pokémon makes physical contact, then there is a 30% chance of the attacker being Infatuated
Using the following attacks:

Name	Type	Cat.	Chance	PP	Att.	Acc.	Effect
Attract			100%	15	--	100	Makes the opposite gender less likely to attack.

There are a few moves that are affected by gender. These moves require the opponent to be of the opposite gender before their effect is implemented. There are currently no attacks which only affect the Pokémon of the same gender of the user.

Finally, there are a few dozen Pokémon who are immune to all of these effects and are in fact devoid of Gender, some still breedable with Ditto but others not being breedable. That said, Mew and Cryogonal both learn Attract which will infatuate other Genderless Pokémon