Koga (anime)

Koga is a Gym Leader appearing in Pokémon: Indigo League.

Season 1: Indigo League
Koga appeared in the episode The Ninja Poké-Showdown, where Ash and company stumble across his Gym. Not appearing until later in the episode, Ash can only find a plethora of hidden traps within the gym, and then later Koga's sister Aya. After the appearance of Koga and a small incident with Team Rocket, Koga and Ash finally have their battle, uninterrupted. The two have a one-on-one battle, with Ash using his Charmander, and Koga using his Golbat. Initially having some trouble, Charmander was unable to hit the Golbat, but after using Fire Spin, Ash was the victor. Upon leaving Koga rewarded Ash with the Soul Badge.

Season 16: BW Adventures in Unova
Koga appeared in Ash's memory when Ash remembered Charizard and his battles.