After a short walk through Route 4, you enter the tunnel to reach Mt. Moon.

Explore Mt. Moon

Go north from the Mt. Moon entrance and you will encounter those Team Rocket people again. After a brief cutscene, they leave.

In Mt. Moon, some of the pokémon you can encounter are Geodude, Zubat, Paras, and Clefairy.

Go west and south from where you encountered Team Rocket to find a Potion.

Go northwest from there and you can battle Bug Catcher Kent. He has a level 7 Butterfree. You get 84 Pokédollars and 3 Poké Balls for winning.

Northwest from Kent, there are 5 Great Balls.

Go back toward the entrance and keep going east. Keep following the path and you will battle Lass Evelyn. She has a level 8 Bellsprout. You get 160 Pokédollars and 3 Poké Balls for winning.

Keep following the path and you'll see one of the Team Rocket people again. She will run away.

Go down the nearby ladder and follow the path. Go down the next ladder and you can battle a Team Rocket Grunt. He has a level 9 Rattata. You get 252 Pokédollars for winning.

Go east from the Team Rocket Grunt to find a Rare Candy.

Go west and go up the ladder, then go east, follow the path, and go up the ladder.

Go south from here and you can battle Youngster Robby. He has a level 8 Mankey. You get 160 Pokédollars and 3 Poké Balls for winning.

Go southwest from Robby and you can battle Super Nerd Jovan. He has a level 10 Grimer. You get 400 Pokédollars and 3 Poké Balls for winning.

To the northwest of Jovan, there is an Awakening.

Go east from here to find an Ether.

Go north from there to find a Repel.

Now go north until you can't go farther north, then go west. You can battle Lass Miriam. She has a level 8 Clefairy. You get 160 Pokédollars and 3 Poké Balls for winning.

Go west and south. You will find one of the Team Rocket people again. He will run away.

Go down the nearby ladder, then go down the ladder in the next room. Go north from there to find a Nugget. Be sure to sell it at a Poké Mart to get a lot of Pokédollars.

Go back the way you came. After you climb up the second ladder, go south. You can battle Youngster Josh. He has a level 8 Sandshrew. You get 160 Pokédollars and 3 Poké Balls for winning.

Go west and you can battle Hiker Marcos. He has two level 10 Geodudes. You get 400 Pokédollars and 3 Poké Balls for winning.

Go north to find a Pearl. You can sell it at a Poké Mart for 1000 Pokédollars.

To the northwest, you can talk to a guy who will give you Poké Balls if you need some.

Go down the nearby ladder.

Follow the path and you will find a Meowth. After it runs away, follow the path and go down the ladder.

Go north from there to find a Revive. Then go south, then east down a ramp. To the east, you battle a Team Rocket Grunt who has a level 9 Drowzee. You get 252 Pokédollars for winning.

Go east from there and you find a Potion.

Go south from there and you will see the Team Rocket people and their Meowth. They will stand there looking at the fossils.

Go southwest and follow the path. Before you battle the Team Rocket Grunt, go east to find a Revive.

Then go north and battle the Team Rocket Grunt, who has a level 9 Zubat. You get 252 Pokédollars for winning.

Now go north and you will battle Super Nerd Miguel. He has a level 10 Voltorb and a level 10 Magnemite. You get 400 Pokédollars for winning. After the battle, you can choose one of the two fossils next to Miguel. If you choose the Helix Fossil, you can use it to get an Omanyte later. If you choose the Dome Fossil, you can use it to get a Kabuto later.

Go north, then west, and Team Rocket will arrive. They demand that you give them your fossil. You battle Team Rocket Jessie and James. This is a double battle, so you will send out two of your pokémon. Jessie and James have a level 12 Koffing and a level 12 Ekans. You get 1152 Pokédollars for winning.

After Jessie and James run away, go west, then follow the path and go up the ladder.

Eastern Route 4

After you leave Mt. Moon, you will be in eastern Route 4.

Go south and jump down the ledge to find a Paralyze Heal. Then go east and north up the ramp, then northeast to find 5 Poké Balls.

Go south until you can't go farther south, then go east to find a Repel.

Go north from here and you will see an item on a ledge. You can't reach the item yet, but check the bush to the left of it to find a hidden PP Up.

Go south and jump down a ledge into some grass. You can find Rattata, Spearow, and Psyduck in this area.

Go east and check behind the bush on the right to find 3 Great Balls.

Keep going east to arrive in Cerulean City.