Oreburgh City is the city that you find after the Oreburgh Gate. It is also a coal-mining town that has beautiful nature. There is a museum that holds onto materials related to coal mining. When you first come here to challenge the Gym Leader, Roark, he is nowhere to be found.
Where is Roark?
The Oreburgh City Gym Leader is missing on your first visit. Go in front of the gym, and your rival will be there. he says he already beat Roark and gained a badge, so now it is your turn to do the same thing. Your rival also says that he is currently at the Oreburgh Mine, and not at the Gym. Go into the mine.
Prepare for Battle!
I recommend going to the Poke Mart before you head to the mine. There are a lot of workers that want to battle you in your first visit.
Yep, Roark is at the mine. His Pokemon Type is Rock, so I also recommend using Water and Grass. He owns a Geodude (Lv12), a Onix (Lv12), and a Cranidos (Lv14).