Appendix:FireRed and LeafGreen walkthrough/Section 18

This is the Bulbapedia walkthrough for Pokémon FireRed and LeafGreen. This walkthrough follows the remade Game Boy Advance version, not Pokémon Red and Blue.
The guide for those can be found here.

Having obtained the National Pokédex upgrade and recovered the Ruby and Sapphire, it is now possible to access Cerulean Cave. The area was previously off-limits because of the powerful Pokémon inside. Head to Route 24 and surf south along the river to reach the cave.

Cerulean Cave

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

This is a treacherous, sprawling cave, so be sure to stock up on supplies. Ultra Balls and the Super Rod should be included in the Bag before heading inside. Fully exploring the cave requires both Surf and Rock Smash, so plan accordingly. The Master Ball can simplify the battle with Mewtwo, but it may be put to better use with the roaming legendary beast.


Head to the water's edge, surf to the island in the northeast corner, and climb the ladder to 2F.

2F (northeast)

Follow the trail to reach a Full Restore behind a pair of breakable rocks, and return to 1F.


Surf westward and climb onto the western platform. Collect the Nugget near the north ladder, then climb up the south ladder.

2F (west)

Break the rock to reach the PP Up, and head back downstairs.


Head south from the platform, and pick up the Full Restore near the group of breakable rocks. Climb onto the platform to the east and take the next ladder.

2F (east)

Smash the rock to reach the Ultra Ball and return to 1F.


Grab the Max Elixir to the northwest, then loop around to the ladder on the central platform.

2F (center)

There are several branching paths, but only one leads anywhere. Loop around in a counter-clockwise direction to reach the ladder near the northwest corner.

1F (west)

This tiny part of 1F simply leads to the basement.


Step down off of the platform and continue on to the northeast corner. Collect the Max Revive from beyond the group of breakable rocks, then turn south. Climb onto the central platform for another Ultra Ball, then head southwest to the water's edge. Surf northwest to reach the final platform.


Not only is Mewtwo the strongest Pokémon around in terms of stat totals, but it is at level 70 when encountered. Save the game before approaching it, as there is only one of it. Mewtwo can restore its health nearly a dozen times with Recover, and is only vulnerable to Bug-, Dark-, and Ghost-type attacks. Without the Master Ball, try using status ailments like Sleep or Paralysis to prevent it from replenishing its health; however, this is a viable alternative only as long as Safeguard is not in effect. For catching it without the Master Ball, use Ultra Balls or Timer Balls once enough turns have passed. Timer Balls can be purchased at the Market Stall on Two Island which can be done anytime after completing the Network Machine quest.

Psychic Unknown
Held item:
Mewtwo Lv.70

With the battle over, use either Dig or an Escape Rope to quickly exit the cave. Having cleared every challenge, the only mission left is to complete the Pokédex for Professor Oak. Remember to show the completed index to the Game Freak employees in Celadon to receive the reward.

Indigo Plateau

By the time Celio connects his Network Machine to Hoenn, Lorelei has returned from Four Island. Each of the five elite Trainers here now have higher-leveled Pokémon with new moves, and in some cases, have added Johto Pokémon to their teams.


Lorelei has swapped out her Slowbro in favor of Piloswine, while her Lapras and Dewgong have learned Thunder and Signal Beam, respectively. Fighting- and Electric-type Pokémon work well against her team, but be careful of Psychic and Earthquake.


Both of Bruno's Onix have evolved into Steelix, but their low Special Defense leaves them vulnerable to Fire and Water moves. His three other Pokémon now know Rock Slide, making this a hazardous battle for Flying Pokémon. Psychic attacks are still useful, and Psychic Pokémon only need to fear his Steelix's Crunch.


Agatha's Golbat has evolved into Crobat, and she has swapped out her Haunter in favor of Misdreavus. Her Arbok has learned Earthquake, and both Gengar know Psychic. In addition, her Misdreavus and her second Gengar know Thunderbolt.


One of Lance's Dragonair has evolved into Dragonite, while the other has been replaced by Kingdra. Kingdra's Water/Dragon typing means that it is only vulnerable to Dragon moves, while it can counter Dragon-type Pokémon with Ice Beam. Both of his Dragonite know moves to counter Water and Water/Ice Pokémon. His Gyarados can cover its weakness to Electric Pokémon with Earthquake, while his Aerodactyl can counter Ice Pokémon with AncientPower.


The rival has swapped out his Pidgeot for Heracross, and his Rhydon for Tyranitar. His Pokémon have much-improved movesets, allowing most of them to cover their weaknesses. Heracross takes massive damage from Flying attacks, but can fight back against Flying Pokémon with Rock Tomb. Similarly, his Tyranitar is doubly vulnerable to Fighting moves, but can retaliate against Fighting Pokémon with Aerial Ace. His Alakazam takes serious damage from Bug, Dark, and Ghost attacks, and physical attacks can exploit its low Defense. Exeggutor has a double-weakness to Bug moves. His Gyarados' Intimidate ability hinders the opponent's offense, while Dragon Dance allows it to improve its own. Arcanine is powerful, but it can only cover one of its three weaknesses. His Charizard is doubly vulnerable to Rock moves, but can counter Rock- and Electric-type Pokémon with Earthquake. Blastoise can cover its two weaknesses—Grass and Electric—with Ice Beam and Earthquake, but its low Speed means it may not have time to use them. His Venusaur knows the powerful Sunny Day-SolarBeam combo, but thanks to its poor coverage, it can easily find itself at a disadvantage.

  Player chose Bulbasaur:   Player chose Charmander:   Player chose Squirtle:

← Part 17 Five Island, Seven Island
FireRed and LeafGreen

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