Things You'll Need
Instructions
Find the uncrossable area at the end of Mount Moon. After defeating Team Rocket, there is a staircase leading directly into a river. Since no Pokemon can use Surf yet, the character cannot swim through the river or walk around it.
Open the Cheats menu, select "Cheat List" and click the "GameShark" button. Enter a description for the cheat. The name doesn't matter but is required. In the box below, enter the code 509197D3 542975F4 78DA95DF 44018CB4.
Walk over the rocks and across the river. Disable the cheat code in the same menu and progress toward Cerulean City.