Glitch: Mew:
To get Mew through a glitch, you should not have defeated the youngster with the Slowpoke by Bill's house or the Gambler between Celadon and Lavender yet. Also, you must have Fly. Make sure to have a weak Pokemon that can safely weaken a Pokemon at level 7, or have some Ultra or Master Balls. Go through the underground passage, and as soon as you exit, do not move. Save the game at this point. Then, walk one step down and immediately press Start. If done corectly, the gambler will not notice you. Go directly to the Pokemon status screen and Fly to Cerulean City. Notice that once you start flying, the Gambler will have an exclamation mark above his head, which indcates that he has noticed you. Once you get to Cerulean City, notice that Start does not work. This is because the game thinks you are in a battle with the Gambler, and Start usually does not function during battles. Walk up Nugget Bridge and find the youngster with the Slowpoke. Do not walk directly up to him or the game will crash. Walk up to him so that he will have to walk over to you. When he notices you, defeat his Slowpoke. Start will work again. Fly to Lavender Town. Go left towards where the Gambler is located. When you get to Route 8, your start menu will automatically appear. Do not save the game. Instead, immediately press B to close the start menu. You will be attacked by a level 7 Mew. Catch it, then save the game.