Glitch Pokémon and glitch moves often have types other than the official 18, known as glitch types. These types do not occur in natural gameplay. Most have no strengths or weaknesses. Some glitch types are exclusive to one specific glitch Pokémon.
'l) m) ZM
The 'l) m) ZM type is found on one glitch Pokémon. Functionally, it is identical to the Steel type.
The ,K Pk<name of player>xX type is found only on the glitch move TM05, which is a move that differs between Pokémon Yellow and Pokémon Red and Blue. Part of the name of this type changes to match the player's name. For example, if the player's name was ASH, the name of this type would be, K PkASHxX.
In the English versions of Pokémon FireRed and LeafGreen, the Gym guide of Vermilion Gym mistakenly refers to the Flying type as the Bird type. This is likely an oversight derived from his dialogue in the English versions of the Generation I games, where he instead refers to Flying-type Pokémon by describing them as "bird Pokémon". Specifically, he says, "Bird/Water-type Pokémon match poorly against the electric type." In the Japanese versions of the Generation I games and FireRed and LeafGreen, he clearly mentions types and correctly identifies the Flying type as ひこうタイプ (the Bird type is とりタイプ in Japanese).
A glitch type is not actually the name of a type. Instead, it refers to a type with no constant name, meaning that giving it a suitable name can be difficult. It is found on six glitch Pokémon and four moves.
Qi JT<name of player>? POké BB<name of Pokémon> de W N
The Qi JT<name of player>? POké BB<name of Pokémon> de W N type is the type of the glitch moves TM14 and TM17 as well as the glitch Pokémonゥ$ (F4). Part of the name of this type changes to match the player's name, and another part changes to match the name of the player's Pokémon at the front of the party. For example, if the player's name was ASH and the active Pokémon's name was PIKACHU, the name of this type would be Qi JTASH? POké BBPIKACHU de W N.
The <class of last Trainer battled> type is found on the glitch move TM28 in Red or Blue versions (TM28 is Bug-type in Yellow), and on one glitch Pokémon. The name of this type is the Trainer class of the last Trainer battled since the save game was loaded, so if the last Trainer battled was a Bug Catcher, then this type's name would be Bug Catcher. If no Trainer has been battled, then the type displayed will be blank.