In 2004, Game Freak released an enhanced remake of the original Pokemon Red game for the Game Boy Advance called Pokemon Fire Red. Over the course of the game, you attempt to rescue abused Pokemon from your primary antagonists, Team Rocket. Interestingly, the game developers included the ability for you to join forces with this nefarious group ... for a price.
Start a new game and select Charmander as your starting Pokemon.
Raise Charmander to Level 50 without evolving into Charmeleon. To do this, rapidly press the "B" button when Charmander starts to evolve.
Go to Cerulean City and defeat the five contenders on Nugget Bridge. A man will approach and give you a nugget for your victory. He will also ask whether you want to join Team Rocket.
Press the following buttons: "A, B, A, B, R1, R1." A box with appear on the screen asking whether you would like to continue.
Select "Yes." The man will confirm your actions by thanking you. You are now a part of Team Rocket! You will lose all of your Pokemon but will gain a Level 5 Mew and a Level 5 Mewtwo.