|Bulbapedia also has an article about ??????????.|
?????????? links here. For the hex:0000 Pokémon Mystery Dungeon: Red Rescue Team and Blue Rescue Team glitch Pokémon, see MD1GlitchDex/00000.
?????????? also called Decamark(s) for short by some people ("deca-" being a prefix meaning "10", combined with "question mark"), refers to many glitch Pokémon in Generation III and the error trap used for them. The exceptions are ?, - (glitch Pokémon) and Bad Egg.
In each game, they occupy index number hex:0000 and everything beyond hex:019D. Some ?????????? are too unstable to be worked with, because while some only freeze the game on the opponent's side, others freeze the game simply by hatching one or when hacking to have a Pokémon evolve into one.
A ?????????? will have a sprite that is a white question mark inside a circle. Certain ?????????? have different versions of this sprite, which may be of a different color palette (possibly even to the extent the visible features of the intended ?????????? sprite cannot be seen), or flipped.
Though the relevant glitch Pokémon will be referred to as "??????????" on the opponent's side, the same glitch Pokémon may have a glitch name on the nickname screen and summary screen, such as a shortened or unchanged version of a move name (e.g. "RBOLT", hex: 0201 instead of THUNDERBOLT) depending on its index number.
Most of the species names and other attributes of the first thousand glitch Pokémon are common between different language versions of the third generation games. However, aside from the species name of the very first glitch Pokémon that are taken from move names, most of a Decamark's Data is completely different between different versions of Generation III games (differences between an English Ruby and an English Sapphire, differences between an English Ruby and an English Emerald, differences between an English Ruby and a Spanish Ruby), leading to hundreds of thousands of different glitch Pokémon across the Generation III Games.
In every Generation III game, when an NPC such as the Slateport Pokémon Fan Club journalist or Two Island old woman reads a glitch Pokémon's species name, the whole species name is read, which overwrites a string of RAM data in the process as they are not properly terminated.
Every NPC that reads a species name except the Pokémon Fan Club journalist will freeze the game when reading a species nam that contains too many characters, usually over 100.
Making a glitch Pokémon gain levels can freeze the game (either because of an evolution attempt, loading the species name, trying to learn too many moves at once, trying to learn a glitch move, or not being able to apply the experience curve.)
In Emerald and FireRed & LeafGreen, a glitch Pokémon's species name is fully read (and fully written in RAM) when the player hovers over the Pokémon in the PC. This RAM writing messes with data related to PC graphics. Changing PC Boxes and selecting Pokémon can quickly and randomly crash the game, while closing the PC will clear off all the graphical issues. An example can be seen here: https://www.youtube.com/watch?v=kOXh7bZRlMo
If the species name is long enough, the overwriting can mess up with the Pokémon selection mechanic and allow for cloning and reverse cloning. Longer names can alter the music as well as the overworld background, though these effects are not retained through saving and soft-resetting.
The cloning procedure also generates a PC Pokémon with data taken from the glitch Pokémon's species name. If the PC Pokémon data is empty enough, an invisible Bad Egg (a corrupted hex:0000) may be generated. An invisible Bad Egg can be used to deposit every Party Pokémon that was alive with a technique called Decaswitch.
The inverse cloning procedure from Glitch Pokémon species name is also the only way to discard Bad Eggs obtained in FireRed and LeafGreen.
Having a glitch Pokémon that allows for cloning and inverse cloning in FireRed and LeafGreen is enough to make these versions autonomous regarding Pomeg glitch setup and thus the Pomeg data corruption glitch, as no more trades from Emerald are needed.
In FireRed and LeafGreen, a glitched species name is always replaced by "??????????" in the summary screen, and its summary sprite is always the unaltered question mark inside a circle.
The PC sprite of a Decamark will always be a copy of the sprite of another Pokémon in the same box, but with a different color palette. The sprites of glitch types can cause heavy graphical glitches in the summary screen.
Some glitch type sprites can turn other PC Pokémon into Bad Eggs if the player views other summaries, or cause the wrong Pokémon's summary to be loaded. As a result, the summary of a slight portion of Glitch Pokémon cannot be opened safely without crashing in FireRed and LeafGreen.
Glitch Pokémon in FireRed and LeafGreen seem to be hatchable with no major issues, as their sprites are stable and their species names are not written in RAM.
In Emerald, only the first ten characters of a glitch Pokémon's name are printed in the summary page.
The Pokémon's second sprite and animation are suspected to be the cause behind the game crashes upon viewing the summary screen.
Most of the glitch Pokémon in Emerald crash the game when their summary page is opened, or when they hatch from an Egg. Thus, a double corruption is mandatory to obtain them in order to not go through a hatching sequence.
In Ruby and Sapphire, the whole species name is read when viewing a glitch Pokémon summary. The glitch Pokémon sprite is always the question mark inside circles.
The RAM writing from viewing glitch types can be used to remove the Safari Mode while inside Safari Zone, even though a large part of the story flags and bag contents becomes corrupted (https://www.youtube.com/watch?v=yD7UCBv0ozA ).
All of the ?????????? can be obtained with the Pomeg corruption glitch by performing a double corruption on certain PC Pokémon, or through the use of a wild Pokémon modifier code for a cheating device.
It is also possible to see the Pokédex entry of a glitch Pokémon by trading data with a save file who possesses that glitch Pokémon in its party and by stealing it from the secret base trainer that appeared after the data exchange.
The hex:0000 variant does not have a glitched name on the nickname screen or summary screen. It is special, because it has its own Pokédex entry programmed into the game in Pokémon Ruby, Sapphire and Emerald and is considered as 'no Pokémon'. It will disappear from the party once captured, even though it is possible to force it in a party.
In Pokémon Ruby and Sapphire, all of its base stats are 0.
[u]Its Pokédex entry in Ruby and Sapphire is:[/u]
"This is a newly discovered Pokémon. It is currently under investigation."
[u]Its Pokédex entry in Emerald is:[/u]
"This is a newly discovered Pokémon. It is currently under investigation. No detailed information is available at this time."
Its species is the "Unknown" Pokémon. It is 0'00 tall and 0.0 lbs.