Are you playing in episode 11? If so, you need to go to the area where the man will tell you about the mudkip. Go the normal route, but once you get to the junction of left or right (right leading to Aya's house) You want to go left, but instead of going down the pole, you want to go up and jump down a ledge. Once there, move forward until you find cave. You'll know its the right cave if it has a rock smash rock and a strength boulder (I hope that didn't sound too confusing )