Now that you have both HM03 Surf and the Soul Badge, you are able to surf on the backs of Pokemon to access even more areas around Kanto, and you might be able to find different aquatic Pokemon. This page is a small list of areas you should go to. Use Fly to quickly get around.
Route 4 Pokemon Battle
Fly over to Cerulean City and walk north to Route 24. Surf back south towards Cerulean City to find a mysterious cave. You won’t be able to enter this cave until you become Pokemon League Champion – it’s far too dangerous. West of this person is a Pokemon Trainer.
Fly back to Celadon City and surf across the small pond in the middle of town. An old man will be standing here. Speak with him to receive TM41 – Softboiled. Softboiled restores the user’s HP in battle, and can restore teammate’s HP outside of battle. The only Pokemon that can learn this Technical Machine are Chansey and Mew.
Route 12 TM
Fly back to Lavender Town and walk south to Route 12. Surf south below the first Trainer on the route to find an item on a platform. This is TM16 Pay Day, an attack that will earn you some extra cash on the side.
If you think you’re ready to take on a tough side quest, stock up on restoring items and as many Ultra Balls as you can. It’s also best to bring a Pokemon that can learn a sleeping attack. A Legendary Pokemon will be waiting.
Fly back to Cerulean City and walk east into Route 9 and 10. Surf southward along the coast to find the hidden Power Plant! More info on the next page.