The Gym Heroes Pokemon Cards, released in June, 2000 , Gym Heroes is the fifth set of cards from the Pokemon Trading Cards Game. It comes after Team Rocket and before Gym Challenge. Its symbol is an amphitheatre with a white stage and black tiers. Amphitheatre (definition) The name amphitheatre (alternatively amphitheater) refers to a level, open space surrounded by an oval area that gradually ascends.
This set also introduced the first layout change, eliminating the flavor text and stacking the weakness/resistance/level to fit the Gym Leader’s headshot/badge.

This is the first set to have Owner’s Pokémon, the owners being the Gym Leaders of the various Pokémon Gyms around Kanto. While all eight Gym Leaders are represented, the most attention is paid to the first four met in the video games: Brock, Misty, Lt. Surge, and Erika. Each of their Pokémon reflect their favorite Pokémon types, as well as Pokémon they have been seen carrying in the TV show. For example, Brock specializes in the Rock-type, so a lot of his cards in the card game are Rock Pokémon. However, in the anime, he also carried a Vulpix, a Fire-type, which is also included in this set.

Owner’s Pokémon must be evolved from a Pokémon of the same owner, which also proved to be unpopular, as the element of mixing and matching cards from different sets is lost. Additionally, some of the “Rare” cards had little or no value in play, such as Misty’s Tentacool, which is incapable of doing damage and is overshadowed by a better version of “Uncommon” rarity. However, Owner’s Pokémon have been sporadically released in Japan, though except for those within EX Team Magma vs Team Aqua, none have been translated into English. This set was originally combined with Gym Challenge in Japan, and due to the division of the set into two smaller ones, odd rarities for Basic Pokémon arose.

This set is also the first set to introduce Stadium cards, trainers that stay in play until another Stadium card comes into play

Gym Heroes Pokemon cards Here