History of the Pokémon types
In Pokémon Red and Blue, there were 15 Pokémon types:
Bug
Dragon
Ice
Fighting
Fire
Flying
Grass
Ghost
Ground
Electric
Normal
Poison
Psychic
Rock
Water
With Pokémon Gold and Silver, two new types were added:
Dark
Steel
Then in Pokemon X and Y, another type was added:
Fairy
There are types that do not apply to any regular Pokémon, only to glitch Pokémon:
Bird
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There is an additional "Shadow" type in Pokémon XD: Gale of Darkness, which is super-effective against every Pokémon type, but not effective against Shadow Pokémon.