Back in an ancient era of video gaming, when a portable console was something risky and unusual, two games, Pokémon Red and Pokémon Blue were released. These games were focused on the collection of 151 Pokémon. However, through exploiting a common glitch, players were able to access some more Pokémon, ones the designers had not intentionally created. The most famous and easiest to access of these is MissingNo, the subject of this article.
MissingNo, and its counterpart ‘M, are the two that most people will most commonly come across. Usually, this involves the old man glitch. The cause of this glitch is related to the low memory environments that the Pokémon developers had to deal with. Each Pokémon in game is assigned a number between 0 and 255 (256 slots). This is not related to the Pokédex number. Each area with grass in it has a list of Pokémon that can be encountered, and the Pokémon are represented by these index numbers in the list. Of course, 256 – 151 means there are 105 unused slots. Under normal circumstances, these won’t have any effect – but there are one or two circumstances where they can.
The circumstances that lead to the game attempting to load the Pokémon at one of these numbers is this:
- When you talk to the Old Man in Viridian City, the game needs to store the player’s name elsewhere, so it can use OLD MAN in its place.
- As the GB did not have much memory, they couldn’t just allocate new storage, and placed it in a part of the memory that wouldn’t be used during the battle.
- They chose the space used for storing grass encounters – after all there is no grass in Viridian City, and when you go somewhere there is grass, it loads the encounter data for that spot, right?
- However, due to an oversight elsewhere, the tiles along the edge of Cinnabar Island are counted as grass. But since they weren’t meant to be grass, there isn’t any encounter data, and the spare copy of the player’s name isn’t overwritten.
- The game attempts to load the player’s name as a Pokémon.
39 of the 105 remaining numbers are used up by different versions of MissingNo. 12 of them are taken up by “Glitch Trainers”. Some of the numbers corresponding to those used for various letters actually do line up to real Pokémon, so you get grossly over-leveled versions of them (128 being the lowest).
So, what else do we know about MissingNo?
- Well, for starters, long before generation II brought in shinies, it had several different forms. The most common was the glitchy mess of pixels, when the data it loaded did not correspond to a valid sprite. After all, if it had the data for a valid sprite, you probably had one of the over-leveled normal Pokémon. Except there were a few sprites that weren’t used for Pokémon in the usual sense. MissingNos 182 and 183 got the sprites from fossils used in the museum of a Kabutops and Aerodactyl. MissingNo 184 got the sprite from the unidentified ghosts in Lavender Tower.
- Certain MissingNos could also be traded to Pokémon Gold and Silver. If they were traded, they often became Generation II Pokémon. For example, MissingNo 184, the ghost MissingNo, would become Pupitar in Generation II. However, the ability to trade them is not consistent.
- MissingNos were slots that originally contained Pokémon that were removed to be placed in Gold and Silver. This is why they’re relatively consistent – It’s blank data in allocated spaces as opposed to the junk data beyond index number 190 with all the weirder glitch pokemon.
- It increases the amount of your 6th inventory item by 128 (255 if caught) beyond the usual limit of 99.
- It scrambles your Elite 4 data.
- It has its own type – Bird, presumably an earlier name for the Flying type.
Now readers who have been paying attention might be thinking: Gold and Silver had 251 Pokémon. 256 – 251 = 5. Were there 5 MissingNos in that game? One slot, 253 is taken up by the Egg. The other remaining slots are taken up by ?????, which, unlike MissingNo, was not likely to be encountered unless you were actively exploiting a more complicated glitch.
If you want more information on Glitch Pokemon, Bulbapedia has articles on many of them, across all generations.