Gym Leaders 09/19/2009
A Gym Leader (Japanese: ジムリーダー Gym Leader) is the highest ranking member of a Pokémon Gym. The main job of a Gym Leader is to test Trainers and their Pokémon so that they are strong and resourceful enough to compete against the Elite Four in the games or the Pokémon League in the anime. If a Trainer defeats a Gym Leader in battle, then the Trainer earns that Gym's Badge. Once a trainer has earned 8 badges from a region, he or she is able to compete against that region's Elite Four or Pokémon League.
A Gym Leader's job is not just to test upcoming Trainers. They must oversee how their respective gym is run and to maintain it. Great care must be taken to make sure that their gym reflects the best environment for the Pokémon type and playing style of choice, usually an environment that suits that type of Pokémon used there (like pools in a Water
-type gym or flowers and plants in a Grass-type gym). According to Morty, teaching young people how to battle with Pokémon can also be the job of a Gym Leader. In the games, Trainers must overcome various obstacles and challenges from other Trainers before they can challenge the Leader. Gym Leaders may also be involved in other activities when they are not battling other Trainers or training themselves, usually something to do with their town's particular attraction or landmark. Gym Leaders can also leave their gyms without notice (as Blue, Giovanni, Jasmine, and Wallace do), and even challenge other Gyms and the Elite Four (like Volkner wanted to do).
It has not exactly been made clear how Gym Leaders attain their position, but it appears that it varies for each gym. Some of them founded their gym and are self-appointed, others appear to be passed on through families, while a few are chosen by the other members of the gym. In the manga series, Red and Falkner have to battle with Pokémon set by the Pokémon League, where those Pokémon are not controlled by Trainers and challenger is not allowed to let any of his Pokémon faint.
Although similar in nature, Frontier Brains are not considered Gym Leaders and are thus not included in this list.