Origins and Inspiration
Pokémon-GX cards were introduced right at the beginning of the Sun & Moon series in the Sun & Moon base set, launched in February 2017. These cards showcase special, powered up forms for Pokémon, inspired by the game mechanic of Z-Moves from Pokémon Sun & Moon. Pokémon-GX cards are often identified by their distinctive borders, a GX extension to the Pokémon's name, and at most times, full-art gorgeous illustrations.
Gameplay Mechanics
A Pokémon-GX card can either be a Basic, Stage 1, or Stage 2 Pokémon which defines how they are played and also evolved in the game. These cards are characterized by increased HP than that of regular Pokémon and more powerful attacks. The balance of this comes in the form of providing 2 Prize Cards when knocked out. One of the unique features of GX cards, however, is their special GX attack: some extremely powerful move which can only be used once per game per player.
Variants and Competitive Impact
Many Pokémon-GX cards will also come in a variety of forms, including regular, Full Art, Rainbow Rare or Hyper Rare, and sometimes even Special Art, drawing collectors in. These cards would form a base for deck-building during the Pokémon TCG's Sun & Moon era and often act as many main attackers or key support Pokémon in strategies. Taking an appearance in all mainstream expansions of the Sun & Moon era, they have also been found in special sets and promotions.
Evolution and Legacy
Introducing Pokémon-GX also introduced Tapu Lele-GX, one of this game's most powerful support Pokémon, whose effects defined the metagame for its whole legal period. New mechanics introduced by these sets, such as Ultra Beasts-GX from GX cards, had special rules and interactions that added depth to the gameplay. In Sun & Moon, a bit later, the mechanic would progress with Tag Team GX to give two or even three Pokémon on one GX card. While current Pokémon-GX cards can no longer be produced in new sets, they have a place in the history of the Pokémon TCG, and they remain legal within the Expanded format of competitive play.