Appendix:Yellow walkthrough/Section 17

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This is the Bulbapedia walkthrough for Pokémon Yellow.
These pages follow the original Game Boy iteration, not Pokémon: Let's Go, Pikachu! and Let's Go, Eevee!. The guide for those games can be found here.

Cerulean City

There is only one place left to explore: Cerulean Cave, a mysterious place on the northwest edge of Cerulean City. To get there, visitors must Surf southward from Route 24.

Cerulean Cave

Cerulean Cave, 1F
Cerulean Cave, 2F
Cerulean Cave, B1F

Cerulean Cave is a mysterious cavern located in the northwest part of Cerulean City. Only the most powerful Trainers who have entered the Hall of Fame are allowed to enter due to the powerful wild Pokémon inside. The sprawling cave network is unforgiving, so be sure to prepare well. Pack the Super Rod and stock up on Ultra Balls, and bring the Master Ball as well. It is here that the genetically-engineered Pokémon from Cinnabar Island's Pokémon Mansion fled after escaping the facility.

1F (South)

Use Surf to swim westward and grab the Max Elixer before climbing the ladder to the west.

2F (South)

Go northeastward to find an Ultra Ball, then backtrack to the south and head east to get a Max Revive. Continue on and climb down the ladder to the northeast.

1F (East)

Surf to the southeast for a Rare Candy, then continue westward. Pick up the Ultra Ball on the rocky ridge, then take the ladder to the south.

2F (Northeast)

Head northwest to find two diverging tunnels. Take the northern trail first to get a Full Restore, then follow the southern trail to the ladder in the far northeast corner.

1F (Northeast)

Go southeast to reach a Max Revive, then backtrack and follow the tunnel westward to the next ladder.

2F (Northwest)

Walk to the southwest to grab a Rare Candy, then climb down the ladder to the north.

1F (Northwest)

Take the next ladder down to the lower floor.


Follow the tunnel to a fork in the road. Collect the Max Elixer from the eastern path before turning southward. Use Surf to reach the rocky ridge in the southwest and collect the Ultra Ball and Max Revive there. Go east, then north to cross the large rocky ridge and pick up an Ultra Ball to the east. Surf southward to find Mewtwo, alone on its island. Be sure to save the game before interacting with it, as there is only one chance to catch it.

VS Mewtwo

Not only is Mewtwo the strongest Pokémon around, but it has already reached level 70. As a Psychic-type Pokémon, it is only vulnerable to Bug-type attacks. Bug moves are fairly weak, and so a better way would be to use the Legendary birds, as they are the closest to Mewtwo's equals in terms of power. The Legendary Pokémon can restore its health repeatedly with Recover, so inflicting status ailments are a must. Not only will this make Mewtwo easier to catch, but Sleep, Freezing, and Paralysis will prevent it from replenishing its HP. It will not let itself be caught easily, so either use the Master Ball when the battle begins or be prepared to go through more than a few Ultra Balls.

Spr 1y 150.png
Psychic Unknown
Mewtwo Lv.70

With the Pokémon League defeated and Cerulean Cave cleared, the only thing left to do is to complete the Pokédex. There are 151 different Pokémon species that have been discovered so far, leaving plenty of training left to do!

← Part 16 The Pokémon League

Project Walkthroughs logo.png This article is part of Project Walkthroughs, a Bulbapedia project that aims to write comprehensive step-by-step guides on each Pokémon game.