The player can obtain these these cards by defeating the eight Club Masters to obtain their respective Master Medals, in a similar style to the Pokémon League, then by defeating the four Grand Masters at the Pokémon Dome. It is possible to defeat the Grand Masters multiple times to obtain multiple copies of the cards.
Only one of the Legendary Cards had been released into an actual card - in the packaging of the Pokémon Trading Card Game, which is only for the Japanese version. This card is the Legendary Dragonite. The other three Legendary Cards in the game cannot be reproduced faithfully for the TCG, as their card effects choose the target Pokémon at random.
This article is part of both Project Sidegames and Project TCG, Bulbapedia projects that, together, aim to write comprehensive articles on video games about the TCG.