The old back version of "Team Rocket Mewtwo" was included in the second gym expansion, "Challenge from the Darkness," released in 1999. The old back versions (1996-2001) were issued in limited numbers, and rare cards with star marks (★) are especially sought after by collectors. Mewtwo, a highly popular Pokémon, is depicted in Team Rocket style (with a dark atmosphere), making it an extremely valuable collectible item. "Team Rocket Mewtwo" has established a solid position among fans of the old back versions as a masterpiece that evokes the history of Pokémon cards.