Although similar to MissingNo. at first glance, the two are separate glitch Pokémon with many differences. They have different index numbers, causing differences such as having the ability to evolve into Kangaskhan while MissingNo. cannot. The similarities that they have are a result of coincidentally sharing a Pokédex number.
cannot be obtained by the Mew glitch because when a Special of any multiple of 256 is used the game will only display a blank text box. can be encountered via the old man glitch with any name other than a default name. This is because it is encountered due to the wild encounter data being read from past the end-name marker. does not appear for a default name like 'RED' chosen directly from the new game interface because these are actually extended 7+ character names using multiple end name characters to hide additional data. The 'absolute name-space' is filled from one of these default names, so invalid symbol 0x00 is not withdrawn. can always appear at level 0 as long as the player's name is not a default name, but can also appear at level 80 if the player's name is a non-default name with an odd number of characters. This is because the game reads the end-name marker (which has an index number of 80) as the level.
's cry while in battle appears to be a slightly different version of Zapdos's cry, having a higher pitch, while its cry when viewing its stats is Rhydon's cry.
It is most commonly known as 'M, since these are the only typographical characters in its name—its real name is impossible to produce with text, and some tiles in its name are not constant. It is also called 'M Block due to either the glitchy blocks next to its name or the Pokémon's boxy shape.
The first two tiles in 's name depend on which sprite is occupying the spot where the player's Pokémon appears. In battle, the tiles on the left of its name will copy part of the sprite in the bottom-left corner of the screen (the player's Pokémon), while the block on the right will copy part of the sprite in the upper-right corner of the screen (the opponent's Pokémon). Out of battle, the blocks in its name will change depending on the player's location.
The encounter flag for MissingNo. and is the highest bit of the 6th item quantity; therefore, encountering MissingNo. or causes the player to get 128 of the 6th item of their Bag if they have less than 128 of that item (this is known as the item duplication glitch). Also, if the player has Hall of Fame data, encountering corrupts it.
and MissingNo. can be uploaded to Pokémon Stadium, and (if the game doesn't freeze) will look like Substitute dolls (small Rhydon-like figures that appear when a Pokémon uses Substitute). 's graphic is blue and MissingNo.'s is purple. When viewed in the Pokémon Center, all of 's stats will be question marks (including the Pokédex species ID number, even though the Game Boy versions identify and MissingNo. as #000). However, will not be allowed to battle, nor will it function correctly in the Gallery (in which players can take pictures of Pokémon). Photos of it will not develop if taken.
If or any other glitch Pokémon is selected in the "see list", the game will freeze, playing the music without the bass track in the background. If a player tries to view 's stats, the game will also freeze on occasion.
can only be used in battle if it is given a nickname. Pokémon Stadium can also allow the player to transfer to Pokémon Yellow, where it will become a 3TrainerPoké $.
In Generation II
cannot be traded to Generation II games because it does not exist in the second generation. In the trade center, appears as a Slowpoke or Tyrogue. When the players try to trade , a message appears stating "Your friend's ('s name) appears to be abnormal." and the trade is canceled automatically. Less often, can be traded, in which case it turns into the Pokémon it was displayed as. can, however be traded to Gold and Silver after it is evolved into a Kangaskhan, Clefairy, or Clefable, even if it has moves that these Pokémon would not normally have (such as Water Gun that originally has, or Fly that can be taught). For example, could be taught Fly then evolved into a Kangaskhan, which could then be transferred to Gold and Silver. However, the Kangaskhan will hold a Carbos instead of a Bitter Berry.
Similar problems present themselves when attempting to transfer or MissingNo. to Pokémon Stadium 2. If successfully transferred, and MissingNo. will become a Ditto.
's height is 23'0''. If it were compared to all other regular Pokémon in terms of height, it would be the 11th tallest Pokémon, tied with Rayquaza. is more than twice MissingNo.'s height.
's weight is 880.6 lbs. If it were compared to all other regular Pokémon in terms of weight, it would be the 24th heaviest Pokémon. 's weight is only about 25% of MissingNo.'s.
's sprite, movepool, and stats are identical to MissingNo.'s, but with two move differences: MissingNo. cannot learn Pound, and is incompatible with TM50 (Substitute).
When the player captures an , the battle will continue with no enemy sprite visible. Capturing "" again will result in capturing a level 0 or 80 Ditto. This happens because the game checks a memory address to determine whether a Pokémon is transformed upon capture. As 's number is outside the usual range, it sets the "transformed" memory address to the incorrect value.
Once gains a level, it will be able to be stored and withdrawn from the PC with freezing.
Additionally, if the invisible Ditto was caught and sent to the PC, it will be able to be withdrawn. Once the Ditto is in the party, it will automatically become level 1. This is due to Ditto being in the "Medium Fast" growth algorithm group.
In the party, will appear as the glitched sprite of a person in the area where the player currently is.
Before is encountered, the black screen before the battle initiates is noticeably longer. This also happens with MissingNo. because invalid Hall of Fame data is saved in the background, though notably not with other glitch Pokémon because they don't actually save this data. The overwritten save data is separate from where main game map/event data is saved, so a 'saved' message is only visible in Pokémon Stadium's GB Tower.
's cry is the cry of Zapdos, but it is slightly higher in pitch.
's Japanese name is "ィ゙ゃゾ┛" in the battle screen, "ィ゙ゃゾ┛A" in the player's party, and "ィ゙ゃゾ▔m" in the Pokédex entry.