To acquire Mew at the earliest point possible in the game, the player must not have defeated the [[Swimmer]] in [[Cerulean Gym]] and the Junior Trainer (the one who says "I saw your
feat from the grass" when the battle with him begins) on [[Route 24]] (West of Nugget Bridge) in the grass. It is prudent to save before doing this. The player must defeat [[Nugget Bridge]] as usual without engaging a battle with the Junior Trainer.
Before attempting this glitch, it is ideal to have several [[Poké Ball|Poké Balls]] stocked up. Note that the player must have an Abra that can teleport, and therefore cannot be playing Yellow version unless he or she has reached Route 5 or traded for one prior to attempting the glitch.