Instructions
Defeat the Canalave City gym. When you obtain the Mine Badge from beating this gym, you will be able to use the move Strength. The move Strength is obtained from the guardians atop Lost Tower.
Fly to Oreburgh City. Head north out of town until you reach Route 206. Do not enter the Cycling Road; instead cut down the small trees blocking the path on the west side of the Cycling Road by using the move Cut.
Continue north until you come to the end of the valley. Walk under the Cycling Road and hug the north wall. There is a small outcropping that leads into Wayward Cave.
Use Strength to move the boulders blocking your path.
Walk around in the cave until Gible appears.