Mewtwo

Description
Mewtwo is a Pokémon that was created by genetic manipulation of a piece of Mew DNA. However, even though the scientific power of humans created this Pokémon's body, they failed to endow Mewtwo with a compassionate heart. Its DNA is almost the same as Mew's. However, its size and disposition are vastly different. It is believed to be the most powerful Pokémon in the world.

Storyline

 * Pewter Gym
 * In Pewter Gym, Mewtwo appears and says that you have to save Joey from Brock, Jessie and James. Then he teleports you and himself inside the Pewter Gym. He throws the Pokéballs away from the center of the gym and teleports away.
 * Vermillion Gym
 * In Vermillion Gym, he appears again. He sees Ash and Mewthree laying on the ground. He runs to Ash, but is caught by Brock with Ash's Master Ball. Then Mewthree stands up and reveals that it just was an illusion of Ash to lure Mewtwo.
 * Saffron City
 * In Saffron City it is revealed that Mewtwo is now in the possesion of Sabrina and that he is hypnotized by Mewthree. You have to defeat him in a battle.
 * Saffron Dojo
 * After you defeated Sabrina, he is back to normal. After a conversation, you have to train to defeat Ash. You also have to steal a Rare Candy from him and other Pokémon of Sabrina.
 * Unknown Dungeon
 * You can catch Mewtwo in the level Unknown Dungeon.

Mewthree
Mewthree also known as "The General" is a Shiny Mewtwo. According to The General, he was one of many earlier and failed specimens, for they were too strong and uncontrollable.

Location

 * Unknown Dungeon
 * Pokémon Adoption:1 SnD Coins (Ready For Battle Non-Shiny Pokémon)

Shiny

 * Shiny Mewtwo has a 0.0125% chance of appearing in the wild.
 * Pokémon Adoption: 5 SnD Coins (Uncommon Shiny Pokémon)

Trivia

 * Giovanni mentioned the creation of Mewthree in Lavender Town.
 * Some people hacked it and try to scam people with it. This happened with Moltres as well.
 * Brock captures Mewtwo in the Vermillion Gym cutscene with Ash's Master Ball, which Sabrina then uses in Saffron City. It is thought that Brock either gave Sabrina Mewtwo or that Sabrina took Mewtwo from Brock.
 * You could get Mewtwo before Unknown Dungeon came out. In the version when the times 2 speed came out, you could use times 2 speed and Pokémon would evolve up two steps up the Pokédex. (e.g. Ivysaur would evolve into Squirtle); if you leveled up a Dragonair to level 55, it would evolve into a Mewtwo.