Blue first appears in Get Rid Of The Ghost Pokémon!! at his mansion in Lavender Town. He meets Red while he was looking at the blue item collection Blue has. He became consumed with hatred towards Red after his Pokémon destroyed his blue item collection. Blue than calls out his Haunter to teach them a lesson. His Haunter was about to give out until it starts to evolve into a Gengar. Gengar appears to be much more of a stronger opponent than before. It turns out that Blue was using his Silph Scope to detect Gengar's movements. Clefairy takes the Silph Scope and Blue can no longer trace Gengar's steps, leaving him at a disadvantage. With the tables turned, Clefairy wins.
Blue reappears in Get The Flying Machine!! where he was fishing with his Blastoise. Blue taunts Red about his Pokémon and demonstrates with his Blastoise on how many fish they caught. When the motorcycle gang came by, Blue watched Red do all the work while he only used his Blastoise to trip the motorcycle gang. After Red deals with them, Blue races with him to the department store. Blue was able to win the race and got himself some jetpacks. He fled on his two Doduo and Blastoise along with Green and his Charizard.
Blue is seen watching a talent show but doesn't participate. However, he does participate in the Sports Meet.
Blue reappears in Seize the Dream of One Million Yen!! as a participant on Giovanni's game show. In the first challenge, he flew on his Blastoise which preventeed him from getting stuck on the slide. In the next challenge, he lied on a skateboard with Blastoise covering him and went through Scyther's slicing of their blades. Blue was not seen in the third one, but in the last one, He was seen watching his Blastoise during the race derby.
In Let's Celebrate the New Year!!, Blue is playing several games with Red, Green, Professor Oak and Giovanni. After the games, he relaxed in a spa with the other competitors and their Pokémon except for Clefairy as he was blasted far away. Blue reappears in The Pokémon Banana League (Part 1) as one of the participants in the Pokémon League. His first opponent was Red, who he thought that he could easily defeat. The battle continued in The Pokémon Banana League (Part 2) with his Mewtwo being the only one left. Red manages to defeat him using his Pikachu and Clefairy, which caused the elimination of Blue.
Blue's reappeared in The End of the Journey!! where he ends up feeling bad for Red after losing Clefairy when he stopped the missile. In Pokémon Snowball Fight, he participates in a race with the other rivals of Red's. After Clefairy built an igloo for himself and his friends, Blue threw a snowball at Red and threw more after revealing himself. However, he was not able to continue due to Clefairy passing gas.
Blue is very obsessed with the color blue, hence the name, and Ghost-typePokémon. Due to his obsession, he will get upset at anyone who destroys his blue colored objects as shown after Red's Clefairy destroyed his property back in the mansion, which resulted in a hatred for Red. Blue is similar to Red's other rival, Green, as they both taunt Red when they win.
Haunter → Gengar
Gengar first appeared as a Haunter challenging Clefairy. Haunter uses one of its illusion techniques to trick Clefairy into believing there was food. Afterwards, it challenges Clefairy to a battle. Even though Clefairy was about to win, Blue commands Haunter to not give up, causing it to evolve into Gengar. Gengar became a tougher opponent for Clefairy than before, as Clefairy was not able to withstand any of Gengar's attacks. However, the Silph Scope that Blue was holding was causing him to have the upper hand. Clefairy took the goggles from him and had the advantage, as it was able to dodge all of Gengar's attacks. Gengar then gets distracted by Clefairy's finger wiggling which made it and Clefairy fall asleep at the same time. Afterwards, Clefairy wakes up and sucks up Gengar in a vacuum. Gengar has not been seen since Blue left his mansion.
Raichu debuted in the Pokémon League. Blue sent it out to battle with Red's Pikachu. Even though Raichu had an advantage due to it being the evolved form of Pikachu, it was no match for Pikachu's speed.
Blue was revealed to have caught this gagMewtwo before his battle with Red. It battled with Red's Clefairy after his Blastoise got beaten. Clefairy managed to win the battle using gag moves despite taking damage from his last opponent.
While Red, Clefairy and Pikachu were in Blue's mansion, they stumble across a Gastly that Clefairy has a fight with. However, since Blue didn't officially control it, it is unknown if it belongs to him, although it is most likely the Haunter that Clefairy fought later.