Summary
Gary’s loss to Mewtwo made him humble and acknowledge Ash’s Pokemon training talent. The defeat forces Gary to reevaluate his behavior after witnessing Mewtwo’s raw power in action. While Gary still teases Ash, the experience had a significant impact on his development as a coach and a person.
Pokémon fans are quite familiar with Ash’s opponent, Gary, and his unpleasant attitude towards Ash and basically everyone else. While Gary has developed as a character, with him putting aside his rivalry with Ash after the climactic battle at the Silver Conference, there was actually a turning point even earlier in their relationship, and that happened when Gary challenged Viridian City’s gym to a fight.
In the episode “Battle of Badges,” Ash runs into Gary near the Viridian gym, where the latter boasts that he actually has 10 badges, more than the eight needed to enter the tournament. He seems to be planning on challenging the Viridian gym just for fun, and beats Ash for only having seven badges at this stage.
Ash and friends lose track of Togepi and are forced to search for it, while Gary continues and enters the gym, challenging the current Pokémon gym leader, Giovanni. Gary easily defeated Giovanni’s first two Pokémon, even despite the type disadvantage, but that’s when Giovanni pulled out his trump card: Armored Mewtwo.
Gary’s loss to Mewtwo forced him to learn humility
Pokémon: Indigo League episode #63, “Battle of Badges”, produced by OLM
Unsurprisingly, Mewtwo defeated Gary’s team, to the point that even being allowed to use two Pokémon at once did not help Gary. Giovanni leaves with Mewtwo and puts the gym under the care of Jessie and James. When Ash and his friends arrived to challenge the gym, they found Gary and his teammates unconscious on the ground, with Gary muttering about a Pokémon so powerful it must be evil. Ash rejects this idea, claiming that the concept of an evil Pokémon is impossible.
Mewtwo’s appearance is tied to the first Pokémon movie, but it still has an impact on the anime’s plot. Gary urges Ash to give up, but Ash continues to fight, giving Gary his first real look at Ash in battle. Gary is impressed and even helps Ash when Meowth tries to sabotage the match further. After Ash defeated Jessie and James, Gary is forced to admit that Ash actually has a talent for training Pokémon.
Gary’s defeat against Mewtwo seemed to be his first major defeat in his Pokémon journey, which was otherwise very easy, as evidenced by all the Pokémon he caught (he had 45 while Ash had 7) and additional badges he earns. Losing to Mewtwo proved to Gary that he wasn’t the strongest trainer, but a rude awakening needed to happen. This situation also forced him to watch Ash’s battle, something he had never done before, and gave him the opportunity to see Ash’s skills at work.
Ash finally defeated Gary in a Pokémon battle in the first match of the Johto League Silver Conference.
Although Gary occasionally irritated Ash after this point, there is no denying that this experience changed Gary’s personality for the better. Even his loss at the Indigo League may not have been enough to force him to reevaluate his behavior, but seeing Mewtwo’s raw power on display did just that. It’s a bit embarrassing Gary did not appear the first time Pokémon movie and gets to interact with Mewtwo again, but the legendary psychic Pokémon still had a major impact on his growth, both as a trainer and as a person.