Missingno. encounter

Be careful around missingno. because the only reason Missingno pops up is because when you surf along the coastline, the game doesn't know which Pokémon you should encounter, and sends out "Missingno.", which just stands for "Missing Number". While you can catch Missingno, doing so can cause your game file to be corrupted, so proceed with caution. and to encounter Missingno. Go to the northern part of Viridian City, and watch the Old Man's demonstration on how to catch a Pokémon. Fly to Cinnabar Island. Surf up and down along the east coast of the island until Missingno appears. (Depending on the player's name, Missingno may not show up, and other Pokémon may appear.)