10 Hilarious But Utterly Game Breaking Glitches

Missingno is the most infamous glitch in Pokémon Red/Blue (and possibly all of gaming). To encounter this... whatever the hell it is, you need to have spoken to the old man who teaches you how to catch Pokémon. Any time after he's shown you the tutorial, fly to Cinnabar Island and surf on the eastern shore until you face this mysterious creature.

Of course, any interaction with Missingno can crash your game (It can happen even if you play Pokémon Red/Blue on an emulator). Nevertheless, it's tempting to look for Missingno since catching it will cause the sixth item in your inventory to increase by 128.

Missingno may be a potential game-breaker but it does cause a lot of funny effects. It usually looks like a reverse-L but can also resemble a garbled mess, a random Pokémon, or even a human. If it takes part in the battle, it can cause its opponent's sprites to flip around. If Missingno is used in Pokémon Yellow, building sprites can duplicate and NPCs may start walking freely through obstacles. If you trade Missingno into Pokémon Stadium, it will appear as a Rhyhorn-like teddy.