From Bulbapedia, the community-driven Pokémon encyclopedia.
Full Art cards are an artwork variant of cards in the Pokémon Trading Card Game. They were introduced in the Black & White expansion, first originating from the Black Collection and White Collection in Japan.
Starting with the Black & White Series, expansions contain Full Art reprints of certain cards from the set. On average, English booster boxes will contain 2 Full Art cards, meaning about 1 card per 18 packs. In Japan, the cards are Secret cards: cards with a number above the set number. The English numbering system places them at the end of the set.
Starting with Next Destinies, many Full Art cards found in expansions are reprints of Pokémon-EX from the same set. The English releases of some Full Art Pokémon-EX feature a special embossed etching treatment.
Cards with Full Art prints