Gary Oak is a prominent character in the Pokémon anime series, known for being Ash Ketchum's main rival. As the grandson of Professor Oak, he is highly knowledgeable and skilled in Pokémon training. Gary is initially portrayed as arrogant and competitive, often taunting Ash with his superior skills and collection of Pokémon. Over time, his character develops into a more mature and respectful trainer, eventually becoming a Pokémon researcher. His journey from rival to ally highlights themes of growth and the importance of friendship in the series.