Beating the Elite Four in Pokemon FireRed & LeafGreen might feel like the goal of your journey while you’re progressing through the gym leader battles, but it’s really just the start. Once you defeat the Elite Four, a whole new world of available Pokemon opens up to you with the National Dex, including a plethora of powerful Legendary and Mythical Pokemon.
One such legendary is Mewtwo, which you can catch in Cerulean Cave after you defeat the Elite Four. However, after the Elite Four, there are a few small things you need to do to open the path to Mewtwo in Cerulean Cave.
How To Unlock Cerulean Cave
To start your long quest to find Mewtwo, you must first defeat the Elite Four and have at least 60 Pokemon registered in your Pokedex.
After you restart the game, Oak will give you the National Dex to help you continue your adventure and catch more species of Pokemon.
If you open your Key Items pocket, you’ll also notice that you have the Aurora Ticket in your bag, which will enable you to reach Birth Island and catch Deoxys, as well as the Mystic Ticket, which unlocks Navel Rock – home to Ho-Oh and Lugia.
To start, go back to Island One of the Sevii Islands, where you’ll be asked to do a post-game quest for Celio, who asks you to find a gem.
To power the machine that gives you access to both Navel Rock and Birth Island, you’ll have to find a Ruby, which is located in Mt. Ember.
On One Island, follow the path east, then north up Kindle Road.
Fight your way north past the Ember Spa and cross the water to reach Mt. Ember, which is currently occupied by Team Rocket.
You can find Moltres here if you didn’t catch it when Bill introduced you to the Sevii Islands during the story.
How To Get The Ruby
The two Rocket Grunts finally made a path in the mountain along the right side. Approach them when they notice you eavesdropping and prepare to battle them both.
Defeat both of these grunts, and enter their newly carved cave path into Mt. Ember.
Follow the linear path until you reach the first Strength boulder puzzle.
- Move the first boulder over until it’s wedged between two rocks.
- Go down and push the southern boulder to the right until it’s also wedged between two rocks.
- Use the newly made path to push the upper rock up against the northern wall, clearing the way for you.
Go into the next room and push the boulder over one tile, then keep going.
At the fork, take the first path to the south and follow it.
Push the boulder out of your way, then go down the ladder into a room with a bunch of strange slabs with the Braille alphabet.
Go further south and down a ladder, and you’ll reach the room with the Ruby that Celio wants. Grab the Ruby, then go back upstairs and out of the Braille room.
You can also use an Escape Rope to leave this cave and return to Celio.
If you don’t have an Escape Rope, go to the room before the Braille slabs, and backtrack northeast.
Further east, you’ll spot two more boulders.
- Push the top rock east against the wall.
- Push the bottom rock west against that wall.
- Go south, then follow the path back outside to return to Celio.
Now, Celio asks you to find a Sapphire to go with the Ruby.
Pokemon FireRed & LeafGreen: 8 Best Late Game Pokemon To Have And Where To Find Them
These Pokemon will carry you through the late game.
How To Get The Sapphire
Now you’ll receive the Rainbow Pass and access to all seven islands of the Sevii Islands.
Head to Four Island now to begin your search. On Four Island, you’ll have to endure a short scene with your rival outside the Pokemon Center, then you can continue.
Bring a Pokemon that can learn Waterfall with you; you’ll need them soon.
Head east of the Pokemon Center, follow the water behind Lorelei’s home, and you’ll find Icefall Cave.
Cross the water inside, then follow the entrance further into the next room.
Cross the patch of ice, then use the left path of ice to follow the route left, then further up.
Step on the northernmost ice patch twice to break it and fall through the floor.
Go up the ladder, then step on the southernmost ice patch twice to fall through it once it’s cracked.
From here, you’ll be on more stable ice. Follow these directions to navigate safely across the ice:
Grab the Full Restore to the left before you move on.
Now you’ll be in front of another item: HM07 Waterfall.
Teach Waterfall to a Pokemon, then jump over the ledge and down to return to the room with the waterfall.
Go up the waterfall, then down the ladder and into the next cave.
Here you’ll find Lorelei battling Team Rocket.
Help Lorelei win the fight, and then travel to Six Island before heading to the Rocket Hideout.
On Six Island, go to the east of the Pokemon Center and follow the path southeast, wrapping around in a maze-like pattern.
Follow the linear path to a door with Braille dots on it.
Use Cut on the door, which will open it. Enter the door to the Dotted Hole, then drop into the hole.
You’ll find a brief puzzle involving four holes, which will lead you to your destination. Drop into the holes in the following order:
Once you do, you’ll be in a room with the Sapphire.
Attempt to collect the Sapphire, and a stranger will drop and steal it from you, then tell you the second password you need to get into the Rocket Warehouse.
Go to Five Island and immediately go right on the sandy shore to Five Isle Meadow. Keep going and defeat a few Rocket Grunts on your way to the door to the Rocket Warehouse.
How To Find The Sapphire In Rocket Warehouse
Enter the password, and you’ll be in the warehouse, faced with a floor puzzle.
Here’s how to solve it:
- Go left and take the top-most arrows.
- Go left again to be spun up and to a red-headed Rocket Grunt to defeat.
- Past the Grunt, take the left group of arrow spinners to a stopping point.
- Go up and battle the Rocket Grunt.
- Stand directly to the Grunt’s left, then take the path left.
- From here, go left and north while avoiding arrows.
- Follow the northern wall to the right.
- Take the down-facing arrows along the far right wall.
- Go down and defeat the Grunt.
Progress into the room on the right and defeat both the Grunt and the Admin here before continuing north.
Now, you can finally face the thief who stole the Sapphire. Defeat him and return with it to Celio.
This will open up access to Mewtwo’s Cave, officially called Cerulean Cave.
How To Find & Catch Mewtwo
Head to Cerulean City, then go to the top left corner of town, where you’ll see the entrance to a cave now open.
Go to Route 24 to the north of Nugget Bridge, then head left and Surf until you reach the cave entrance.
Enter the cave with the strongest Pokemon team you have and prepare for a fight unless you’ve packed plenty of Max Repels.
Pokemon here will be between levels 46 and 70.
Make your way to the lower section of the cave, where you’ll finally be able to encounter Mewtwo at level 70 in the basement.
Bring a team composed of Snorlax, a status-inflicter, like Gengar, Dragonite, or Golbat, and something that knows Dragon Rage to deal controlled damage to Mewtwo.
Whittle down its HP and either put Mewtwo to sleep or paralyze it. After plenty of effort and Ultra Balls, Mewtwo will be yours.
If you want to shiny hunt Mewtwo, make a save right before encountering it, and if Mewtwo is not shiny, press A, B, X, Y to reset and start again.
Pokemon FireRed & LeafGreen: How To Get All Eeveelutions
Get your Eevee gift for free and choose your evolution.
