The title of this article is incorrect because of technical limitations. The correct title is ?????.
????? is a glitch Pokémon in Pokémon Brown. It replaces all the garbage data from Pokémon Red which is not taken by any Pokémon from a later generation. Because values above 200 generate trainers, only the ????? found in hex 00 is obtainable without hacking. (It can be found using either the Mew glitch or the Old Man glitch.)
Item corruption glitch
When encountered, the ????? found in hex 00 corrupts the second item in the player's inventory, adding 128 (2^7) to the identifier. Glitch items are obtainable in this way; for example, if the second item is an Ice Heal, it becomes a nameless item which enables the player to walk through walls.