Instructions
Enter Mt. Mortar using the entrance leading from Route 42.
Summon a Pokemon that has the ability to "Surf" and use it to go straight up the body of water until you reach a waterfall.
Use a Pokemon's "Waterfall" ability to scale the waterfall.
Continue straight until you reach dry land. Locate and enter another cave entrance through the back.
Take a sharp right and surf through the small patch of water and land on another piece of land. Head north until you reach a few bushes. Take an immediate left and head east until you get to another piece of land.
Walk a couple of steps and turn south until you see a ledge. Jump down from the ledge and walk immediately eastwards. Continue to walk straight until you reach a dead end.
Turn south and hop over a ledge. Use your Pokemon's "Surf" ability to navigate through the last body of water before reaching the Karate King.
Follow the body of water eastwards until you reach land. Continue on the land, up a few steps, until you see the Karate King on your left.