Spoiler: show
Ok, has anyone tried the Mew Glitch? You may already know this, but to properly perform this glitch, a player must have had acquired the HM containing Fly or have a Pokémon that knows Teleport, and must have avoided the Youngster on Route 25 and the Gambler near the underground path, right of Saffron City, until ready to perform the glitch. First, a player must stand above the Gambler so that he is no longer visible. Next they must take a step down at him and quickly press start to open the menu (Note: If the Gambler spots the player the glitch will fail). While the menu is open, Fly to Cerulean City. If this step is performed correctly, the Gambler will spot the player, but the player will fly away right before the Gambler approaches him. Once the player arrives in Cerulean City, they are unable to talk or use the menu. Next, the player must battle the Youngster on Route 24 that was avoided earlier (Note: When going to battle the Youngster, the player must be a few steps away from him so that he walks to the player. Standing right in front of him will cause the game to freeze. The music will still be playing and, if you tried to talk to him, he will face you when you pressed A.). After defeating him, Fly to Lavender Town and walk onto Route 8, this will cause the start menu to pop up. DO NOT DO ANYTHING! Simply exit the start menu. Once you exit, the player will be put into a battle with a Lv. 7 Mew.
Another way is the version in Cerulean City. First, you need a Pokémon that knows Teleport. Then, player must stand above the Youngster so that he is no longer visible. Next they must take a step down at him and quickly press start to open the menu and Teleport to Cerulean City. After that, you will notice that the menu is unusable. Battle the first trainer in the Cerulean City Gym, then head to the Nugget Bridge. When you get to the bridge, the menu will suddenly appear. Press B and Lv. 7 Mew will appear. You can also encounter other pokemon this way.






