Type (TCG)
Elemental types play as large a part in the Pokémon TCG as they do in the Game Boy games. Both Pokémon and Energy cards can be one or more of these types. Similarly, a Pokémon can and probably will have a Weakness and Resistance to other types.
Unlike in the Game Boy adventures, there are only 9 types.
Also, unlike the Game Boy adventures, when a Pokémon attacks, the type of damage it does is based on the Pokémon's own elemental type and not the type of Energy the attack requires. For example, although Dark Golduck uses Psychic energy to power both of its attacks, the attacks do double damage against a Pokémon weak to Water because Dark Golduck's TCG type is Water in this instance.
Because of the limited number of types, many of the 17 types found in the Game Boy adventures have been combined into one of the TCG types. For example, Poison-, Bug-, and Grass-types in the Game Boy adventures are instead combined into the Grass type in the TCG (until Diamond & Pearl, when Poison Pokémon were moved to the Psychic type). However, in keeping with Pokémon tradition, the Weakness and Resistance of certain Pokémon are similar to their weaknesses in the Game Boy adventures. For example, even though Glalie is a Water-type in the TCG, it is weak to Metal, much like how in the main series, Glalie, as an Template:Type2, is weak to Steel.
Another difference between the Game Boy adventures and the TCG is how damage is calculated according to Weakness and Resistance. Prior to Diamond & Pearl, if a Pokémon had a weakness to another Pokémon's type, the damage done was doubled, and if a Pokémon had a resistance to another Pokémon's type, that damage was reduced by 30 damage points, rather than being halved. In Diamond & Pearl and later, weakness and resistance are typically fixed amount increases and decreases, though some Pokémon still use the original doubling weakness.
Sometimes, special Pokémon, such as Pokémon ex and the like, will have more than one weakness or more than one resistance. Likewise, other special Pokémon may have more than one type, a feature introduced in the EX Team Magma vs Team Aqua expansion, with Pokémon that were part Darkness and part their normal type. Eventually, the EX Holon subseries would introduce Pokémon with another secondary type, this time Metal.
