A Theme deck, previously known as a Preconstructed Theme Deck, is a playing deck of Pokémon Trading Card Game cards sold pre-packaged alongside mainstream card sets. Most Theme decks are designed with a specific strategy (such as Special Conditions) or theme (such as starter Pokémon) in mind.
Theme decks are mostly seen only alongside English-language releases and are seldom released in Japan, released only alongside debut sets such as Base Set and Neo Genesis, as well as alongside the original Gym sets. The vast majority of Japanese decks released are Half Decks and are released alongside almost all sets.
For English-language set releases, most expansions are assigned two theme decks affiliated with the set, with the next most common number being three theme decks for releases such as EX Crystal Guardians, Diamond & Pearl, Great Encounters, Black & White and Kalos Starter Set. Only three sets have included four theme decks so far (Gym Heroes, Gym Challenge and HeartGold & SoulSilver), only two sets have included five theme decks (Base Set and Base Set 2), and only three mainstream sets have included no theme decks (Neo Revelation, Dragon Vault, and Legendary Treasures). In addition, there are Online-exclusive Theme decks for the Pokémon Trading Card Game Online.