Selene

Selene (やみこ Yamiko) is the Gym Leader of the Watsonia Gym, officially known as the Watsonia City Gym. She specializes in Dark-type Pokémon and gives out both the Void Badge as well as the to trainer's who defeat her.

On the Wiki
Selene in the sixth Gym Leader in the Hora Region, as well as the youngest, being younger than Lorraine by a few years. She specializes in Dark-type Pokémon and gives out both the Void Badge as well as the to trainer's who defeat her. Unlike the other leaders, her entire family have been dead since she was five. She grew up in the care of the Pokémon Gym's trainers, inheriting her parent's Pokémon and becoming Gym Leader at the age of 10. She loves Dark-types, and has an interest in the Dark-type Pokémon Darkrai.

On Hand
This section is for the Pokémon Selene constantly has on her, that regularly participate in Gym Battles. Side from Zoroark, these Pokémon most likely belonged to her parents:

In fanfiction
In Light and Dark, Selene is similar to her "default" persona, with a few noticeable differences. Like the default, Selene is the sixth Gym Leader of the Hora League, in addition to being the youngest leader in Hora, next to Lorraine. She gives out the Void Badge to those who managed to defeat her. She is a specialist in the -type, though she also enjoys taking part in. In Light and Dark, originally, she was an orphan, growing up in the care of the Gym trainers that would eventually become her loyal followers, until she was made the Gym Leader at the young age of ten.

Selene is fiercely competitive, not only in her Gym battles, but also in the Pokémon Contests she takes part in. This can cause her to appear fiery and vain, even when she doesn't mean it. She seems to care a great deal for her Pokémon and has an outstanding relationship with each of them.

In Gible, Gabite, Garchomp!, she shows a fierce respect for Wallace; getting violent when he is talked poorly of.

Trivia

 * Selene's name is pronounced the same as another Dark-type Specialist, Celine.
 * Selene has two Psuedo-legendary Pokémon.