Gym Heroes arrived in 2000 as one of the earliest expansions printed after the original Base Set boom. The set introduced Pokémon tied to gym leaders from the trading card game's lore, offering players and collectors a fresh thematic direction. These early expansions remain foundational to the hobby, representing the period when Pokémon cards transitioned from cultural phenomenon to established collectible category. Brock's Rhyhorn captures one of the franchise's most memorable gym leaders with his signature rock-type Pokémon. The card showcases vibrant gym-era artwork that collectors appreciate for its nostalgic character portrayal. Brock's cards from this period hold particular appeal for fans of the original anime series and those building complete gym leader collections.