Pokemon
¤ Red and Blue
¤ Red and Green (Japanese)
¤ Blue Version (Japanese)
¤ Yellow Version
¤ Gold and Silver
¤ Crystal Version
¤ Ruby and Sapphire
¤ Emerald Version
¤ FireRed & LeafGreen
¤ Diamond and Pearl
¤ Platinum Version

Universal Information
¤ What is this section?
¤ Breeding Pokemon
¤ Evolution Methods
¤ Elemental Types
¤ Pokerus Infection
¤ Shiny Pokemon

Affiliates
¤ Amity Square
¤ Dark Eon Hideout
¤ Eevee's Headquarters
¤ Eevee's Mansion
¤ Jenviousity
¤ Lugia's Island
¤ Perfect Absolution
¤ Pokemon Battle Dome
¤ Pokemon Inferno
¤ Pokeshore
¤ PokeTech
¤ Pokeuniverse
¤ Pokemon Valley
¤ Sapphire Milotic
¤ The Spriting Shack

Fly to Cerulean and head for Nugget Bridge. At the end, Surf in the water and follow the watery path. Reach land and enter the cave. It is no longer blocked.

Head for the raised platform and Surf. Keep going until you reach land at the end of the path. Head south and follow the rock lined platform to a ladder. Down below, take the lower path. When it forks, take the left side. It will lead you to the lower floor.

This floor is straight forward. Follow the paths and Surf when needed. Soon, you'll come across Mewtwo at Level 70 on his small island. He is a hard catch unless you have a Master Ball. Throw the ball to catch him. If you wasted the Master Ball, weaken him to a sliver of health and put him to sleep. Freezing Mewtwo is also acceptable. Throw Ultra Balls with great hope until you catch him. You may end up retrying a couple times, but don't give up!