From Bulbapedia, the community-driven Pokémon encyclopedia.
The Expanded format of the Pokémon Trading Card Game is one of two formats used for officially-sanctioned Play! Pokémon events. It was added to the Standard format in the 2014-2015 season. It allows a greater number of expansions than Standard format but is not as unpredictable in card combinations as Unlimited format. It is also used in the Pokémon Trading Card Game Online.
It remains to be seen if Play! Pokémon will begin rotating out sets once per year, after the World Championships, as they currently do with Standard format. Additional expansions are added to the current Rotation three weeks after they are released in the United States.
If a card in an Expanded-legal expansion is a reprint of an older card, all prints of the card can be played in an Expanded-legal expansion-legal deck (i.e. Base Set Potion, recently reprinted in Black & White). However, some cards significantly differ in wording between older prints and newer prints (i.e. Charizard from the Base Set compared to its Stormfront iteration); those cards require a reference outside the deck in order to use the older prints in a Expanded-legal deck. A reference must be either a new version of the card or a printout of the card's entry from the official Card-Dex.
Play! Pokémon requires players to play with cards printed in their region's official language (for example: players in the United States are restricted to English cards only, whereas players in Canada can use cards in English and cards in French).
List of Expanded formats
In other languages