Pokémon Red and Blue/Cascade Badge

Route 3

After defeating Brock, the man who was blocking the east exit from Pewter City will be gone. This leads to Route 3. The first part of this area is home to eight enemy Trainers in close proximity to each other. You will find a patch of tall grass near the eighth Trainer. After that, the Route opens up. There will be a man (but who is not an enemy Trainer) standing next to a sign and a patch of tall grass. Head north from here. You will soon encounter a Pokémon Center, out in the middle of nowhere. To the east of the building is a cave entrance.

Inside this Pokémon Center is a man who will offer to sell you a Magikarp for •500. This is not that good a deal, because later in the game you will receive the Old Rod, which can catch an infinite number of Magikarp at any watered area.

When you’re ready, enter the cave.

Mt. Moon

Mt. Moon is a large cave, with many tunnels and three floors to explore. This is the most effective way to fully conquer Mount Moon:

Starting at the entrance to the cave, go north until you reach the sign. The large room to the west contains TM 12 (Water Gun) and a Potion, as well as one enemy Trainer.
Return to the sign and go east, past another enemy Trainer. You will soon encounter a ladder. Step on the ladder and you will climb down to the next floor.
The first basement floor of Mount Moon is nothing but a collection of straight tunnels. Traverse the one you’re in and continue down the next ladder.
You will arrive in an enclosed area with an enemy Trainer, the first member of Team Rocket you will battle in this game. Past him is a small pedestal area that holds an HP Up.
Go back up both ladders, then head south. This part of the cave contains two enemy Trainers and three items: a Potion in the southwest corner, a Rare Candy in the southeast corner, and an Escape Rope north of there. Continue north past where you find the Escape Rope.
To the northwest there will be another ladder. Go down it, traverse the straight cave, and go down again. You will now be in a different enclosed area on the lowest floor of Mount Moon. Here you will find another member of Team Rocket, TM 01 (Mega Punch) on the pedestal, and behind the rock to the east, an Ether.
Go back up the ladders. Continue down the path until you reach the large room. In the northeast corner is an enemy Trainer, a valuable Moon Stone in the very corner, and another ladder down.
Go down the ladders. You will now be standing on a raised platform near where you found TM 01. Follow the path all the way around, battling two Team Rocket members as you go. Past the second Team Rocket member is a doorway-like formation. Immediately after you pass through it, go east. You will see a small, one-tile-sized dead-end passage. Enter this passage and examine the tile closest to the wall. Even though you can’t see it, you will find another Moon Stone here.
Go up the stairs. The enemy Trainer you battle here will be, interestingly, not a Rocket. He is the last enemy Trainer in Mount Moon. After you defeat him, you will be offered the choice of one of two items: the Dome Fossil and the Helix Fossil. Both items, while worthless right now, can be exchanged towards the end of the game to receive a Pokémon you can’t get anywhere else: The Dome Fossil will yield a Kabuto, while the Helix fossil turns into an Omanyte. Whichever fossil you do not choose is lost forever.
Past there, you will find another ladder. At the end of one more straight cave, you will find that when you step on the last ladder you will exit the cave onto a new Route.

Note that the Escape Rope you find here can be a useful item. If you use it, you will immediately be teleported out of wherever you are in the cave and respawn at the Pokémon Center just outside Mt. Moon. (You will have to walk back to where you were, though.)

Route 4

This large, open route is your last step before reaching Cerulean City. There are two items here. The first is TM 04 (Whirlwind), which is in plain sight on top of a hill. The other item, a Great Ball, is hidden. Just as you leave Mt. Moon, go northeast to find a sort of plateau made of ledges; the item is hidden somewhere in the middle.

Once you reach the far side of Route 4, you will have to jump a ledge that you cannot then climb up again. Once you do so, you will be trapped in the area around Cerulean City. There is a small patch of tall grass here, if you need to train your Pokémon.

Cerulean City

Cerulean City is the same size as Pewter City, but is much more dense. There are four exits from this city; you came from the west one. The north exit leads to Route 24. The east and south exits are currently inaccessible.

You will find the Bike Shop in the southwestern corner of the town. You might think that the bike is impossible to obtain, since they are charging •1 million for it and the maximum money you can hold at any one time is •999,999. However, you will soon receive a Bike Coupon that you can use here.

Cerulean City Gym

The Cerulean City Gym is a series of platforms over a large pool. There are two enemy Trainers between you and Misty; the first can be avoided. The Trainers here use Water-type Pokémon. Please see the Enemy Trainers section of this guide for information on the Pokémon you will encounter in this Gym.

Boss — Misty (•2079 reward)

Level 18 Staryu
Level 21 Starmie

After you defeat Misty, you will receive the Cascade Badge. While receiving the Cascade Badge does not grant any boost in battle, it enables you to use traded Pokémon up to level 30. (If you trade in a Pokémon of higher level than this, it will refuse to attack in battle.) This badge also grants you the ability to use the Cut move outside of battle. You will also receive TM 11 (Bubblebeam).