Blue Oak is the player's rival in Pokémon Red, Green, Blue and Yellow and in the FireRed and LeafGreen remakes. He is Professor Oak's grandson and Daisy's younger brother, a childhood friend of Red who turned cocky as they grew up. He always takes the first partner Pokémon whose type beats the player's, and in Yellow he grabs the Eevee Oak meant for the player. After challenging the player at intervals across Kanto, he beats the Elite Four and becomes Champion, only to lose the title to the player moments later. Professor Oak then arrives and tells him he never learned to care for his Pokémon.
In Gold, Silver, Crystal, HeartGold and SoulSilver, set three years later, Blue has taken over the Viridian Gym that Giovanni abandoned. Like Giovanni he has no type specialty and awards the Earth Badge, and he wanders off often enough that challengers have to find him first. He returns in the Pokémon World Tournament of Black 2 and White 2, as a Battle Tree leader alongside Red in Sun, Moon, Ultra Sun and Ultra Moon, and as the new Viridian Leader in Let's Go, Pikachu! and Let's Go, Eevee!. His anime counterpart is Gary Oak.
Blue's Tactics, a Supporter from Unified Minds (2019), refills a hand instead of drawing a set number: at the end of the turn it is played, its player draws until holding eight cards. The Uncommon (#188) is illustrated by Megumi Mizutani, who also drew Blue's Let's Go artwork, and the full-art Ultra Rare (#231) by Naoki Saito.
The Uncommon printing, illustrated by Megumi Mizutani.
The full-art Ultra Rare version, illustrated by Naoki Saito.
Green is his original Japanese name; English releases call him Blue. The anime's version of the character is Gary Oak.
No. The player takes the title from him right after he wins it, and by Gold and Silver he leads the Viridian Gym, awarding the Earth Badge.
At the end of the turn you play it, you draw until you have eight cards in hand. Unified Minds (2019) printed it as an Uncommon and a full-art Ultra Rare.

CHAMPION
4 Trainer cards · 0 partner Pokémon
Blue, called Green in Japan, is Professor Oak's grandson and the player's rival in Pokémon Red and Blue, reaching the Champion's seat just before the player takes it. By Gold and Silver he runs the Viridian Gym. His Supporter card is Blue's Tactics from Unified Minds (2019).
No published index yet — too few of Blue’s cards trade often enough to strike one.