Pokémon Gold Version, Silver Version, and Crystal Version - Walkthrough - Backtracking

→ Pokémon Gold Version, Silver Version, and Crystal Version - Walkthrough - Backtracking

This information might be useful when playing Pokémon HeartGold Version and Pokémon SoulSilver Version, too.

Now that you have Fly, it’s time to do some backtracking. Do any of these if you haven’t already done so:

Fly to Violet City, and go east. Find the chubby man by the fruit-bearing tree, and return the Spearow (make sure he’s in your party) to him. He’ll give you TM50 (Nightmare). When you return to the gate from Goldenrod to Route 35 the guard will give you an HP Up.
Your Egg may have hatched into Togepi. If it has, fly to New Bark Town, and show the Egg to Professor Elm in his lab. He’ll give you an Everstone, which prevents Pokémon from evolving.
Fly to Azalea Town and visit Slowpoke Well. Use Strength to push the stone out of the way, and continue and surf your way to a man who will give you a King’s Rock.
Go to Route 34, and surf on the water to the left. Surf down, and three girls will challenge you to battles - one after the other. It’ll be tough, but you’ll receive Soft Sand in the end.
Go to Cherrygrove City. Surf on the sea, and the fisherman you’ll soon see will give you a Mystic Water, which powers up water type moves.

After doing all of this, fly to Ecruteak City, and take the route east, surf through the water, and you will reach Mahogany Town.