A.J. (Japanese: アキラ Akira) is a Trainer who lives between Cerulean City and Vermilion City. His dream is to become a Pokémon Master with the help of his favorite Pokémon, Sandshrew. He ran an unofficial Gym which was not sponsored by the Pokémon League and therefore did not give out any Badges.
A.J. was the character of the day in The Path to the Pokémon League.
In this episode, Ash, Misty, and Brock were on their way to Vermilion City, when they heard about a local Trainer who was undefeated. Ash, eager to challenge this Trainer, went to A.J.'s Gym and saw a sign above it announcing that A.J. had been undefeated through 98 matches. A.J. returned to the Gym after catching some wild Pokémon. Ash then challenged him to battle number 99.
Ash began to say how he thought low about a person with 98 victories but without a Gym Badge. A.J. responded with saying that he wasn't planning on challenging a Gym Leader until he had 100 wins in a row. Ash bragged about the two Badges he had at the time just with ten victories, and A.J. insulted him and said he must have gotten them from weak Gym Leaders, which angered both Brock and Misty. A.J. defeated Ash with his Sandshrew without much effort, causing Ash to complain and accuse A.J. of cheating.
As the group was about to leave, they looked inside the Gym, and they saw A.J. using a whip to send his Sandshrew diving into a pool. Ash attacked A.J., thinking that he was torturing his Pokémon. A.J. then explained that he was strengthening his Sandshrew's resistance against water. Sandshrew and all of A.J.'s other Pokémon were wearing Macho Braces to intensify their strength. He also had all of his Pokémon exercise in rigorous routines. Ash complained about A.J. treating his Pokémon too harshly, and asked Brock and Misty to back him up. However, instead Brock complimented A.J. on the specialized foodhe prepares for his Pokémon.
Jessie, James, and Meowth then tried to steal Ash's Pikachu, but ended up accidentally taking Sandshrew instead. Not knowing what had happened, Ash guessed that Sandshrew had run away, and offered A.J.'s other Pokémon spots on his team, but they ignored him. Sandshrew escaped from Team Rocket by using Dig, accidentally bringing Meowth along with him. After A.J.'s Sandshrew came back, he challenged Team Rocket to a battle, and his Sandshrew defeated Team Rocket, winning A.J. the final victory needed to set off and collect Gym Badges.
After A.J. and Sandshrew had been happily reunited, Ash realized that A.J. cared deeply for his Pokémon, despite being tough on them during training.
A.J. made another appearance in a flashback sequence of the Orange Islands opening song Pokémon World. He and his Sandshrew appear with a group of other Trainers Ash encountered during his first trip through Kanto.
In Pokémon Yellow, a game based on the anime, there is a Youngster on Route 9. This Trainer solely uses a level 24 Sandshrew that has the move Fissure, much like A.J.'s Sandshrew in the anime. After the player wins the battle, he says, "I'll restart my 100-win streak with Sandshrew," a reference to the fact that A.J. won 100 battles. This Trainer may be A.J., or a reference to him. In Pokémon Red and Blue, this Trainer is originally a Jr. Trainer♂, has a Growlithe and a Charmander, and says, "Keep walking!" after being defeated.
- A.J. bears an uncanny resemblance to both the official Generation I artwork for the Cooltrainer, as well as the Generation I sprite for the Cooltrainer. The significance of this resemblance is unknown, especially since he is portrayed as a Youngster in Pokémon Yellow.
- A.J.'s Sandshrew used Defense Curl, despite that Sandshrew couldn't learn it until the next generation in the games.