From Bulbapedia, the community-driven Pokémon encyclopedia.
The Oreburgh Gym (Japanese: クロガネジム Kurogane Gym) is the official Gym of Oreburgh City. It is based on Rock-type Pokémon. The Gym Leader is Roark. Trainers who defeat him receive the Coal Badge.
In the games
The Oreburgh Gym is a narrow building built of stone. Two paths exist, a raised path that avoids the Trainers and a middle path that takes challengers straight through the Gym. Roark waits on a raised hill at the end of the paths. Although only two Trainers actually appear in the Gym, most of the miners in the Oreburgh Mine are also members who relax at the Gym in their free time. While Roark is the Gym Leader here it is revealed that Byron had originally asked Riley to be the Gym Leader here until Riley turned it down in favor of Roark.
The Gym as depicted in Diamond, Pearl and Platinum
In the anime
The Oreburgh Gym first appeared in Shapes of Things to Come!, when Paul challenged Roark. Ash watched this match, and in the next episode lost to Roark because his concentration was instead on besting Paul. After some heavy training in Wild in the Streets! and some advice from Dawn, Ash re-challenged Roark in O'er the Rampardos We Watched!. This time, he won the match, gaining his Coal Badge. In Ancient Family Matters! it was revealed that prior to Roark becoming Gym Leader, his father Byron was the Gym Leader, but ultimately left to become the Leader of the Gym in Canalave City.
In the manga
In Pokémon Adventures
The Oreburgh Gym is the first Gym that Platinum challenged and was featured in A Conk in Cranidos's Cranium. Diamond and Pearl were thrown out by the Gym Statue for the duration of the Gym challenge, consisting of Gym Trainers and the Gym Leader himself. They, however, helped Platinum to win the battle against Roark from the outside by concealing information in their manzai routine.