When Misty returned to Cerulean City to fill in for her sisters as Gym Leader in Cerulean Blues, she found out that a newly-evolvedGyarados was on a rampage at the Cerulean Gym. Even worse, PIA inspectors were ready to condemn the Gym if there was no leader to keep Gyarados under control. Panicking, Misty tried many attempts to stop it, including a reenactment of the water ballet show Gyarados participated in as a Magikarp. When none of these methods worked, Misty resorted to locking it in a cage. However, after the Invincible Pokémon Brothers had an unfair battle with Misty, they got their Tentacruel to attack it with Poison Sting. Misty then took the attack for Gyarados, causing Gyarados to earn her trust. Calmed, it finally allowed her to return it to its Poké Ball.
The use of Gyarados is significant, since Misty had been afraid of the species up until this point. This came from a traumatic event that occurred during her childhood, when she had crawled into the mouth of a sleeping Gyarados and was almost swallowed by it.
Gyarados reappeared in When Regions Collide!, where it was used to battle against Ash's Pikachu. The two started with a collision of Hydro Pump and Thunderbolt. Pikachu then rushed towards Gyarados and made a direct hit with Quick Attack, sending Gyarados flying. Pikachu then started charging up Electro Ball and Gyarados used Rain Dance, confusing everyone. Ash instructed Pikachu to ignore the rain and attack. However, Gyarados countered with a Rain Dance-powered Hurricane, which destroyed the Electro Ball and sent Pikachu flying. Deciding it was time to get serious, Misty revealed her Key Stone and Mega Evolved Gyarados into Mega Gyarados.
After Mega Evolving, Gyarados launched a Hydro Pump that destroyed the rock Pikachu was standing on, sending him flying into the water in the battlefield. Not letting up, Gyarados tried to attack Pikachu with Crunch, but was struck by Iron Tail after Pikachu got behind it. Gyarados dove underwater and used Hurricane, creating a cyclone of water around Pikachu. Ash ordered Pikachu to use Thunderbolt to break it up, but the strategy was unsuccessful. Misty assured Ash that no Trainer had ever beaten this strategy. Ash instead ordered Pikachu to run on the electricity with Quick Attack, which allowed to Pikachu jump out of the cyclone. The two then performed their Z-Move, Gigavolt Havoc. The attack hit Gyarados head on, defeating it and giving Ash the win.
At first, Gyarados was very angry and enraged, attacking every nearby person and Pokémon and not calming down for a second. This contrasts with its personality as a Magikarp, when it was much more relaxed and had once even participated in a water ballet with Misty. Its rage as a Gyarados even made it unwilling to go back into its Poké Ball, forcing Misty to confine it in a cage to avoid any further damage to the Gym.
However, when Gyarados saw how much Misty cared about her hurt Corsola, its personality started to become calmer. When Misty took the Tentacruel's Poison Sting in order to protect Gyarados, and was on the brink of drowning, Gyarados broke out of its cage and brought Misty to the surface, showing that it now had full confidence in her. By this point, Gyarados even listened to her commands and was willing to go back into its Poké Ball. This bond has remained between Misty and Gyarados ever since, making Gyarados one of Misty's primary battlers.
Misty also has a Gyarados in the manga counterpart to the anime, but, unlike in the anime, it was the first Pokémon she ever caught. She trained it carefully until it evolved and, due to this, it's extremely loyal to its Trainer.
Gyarados appeared in Play Misty For Me when Ash challenged the Cerulean Gym. At first Ash tried to send Pikachu into battle but the Electric Mouse was too scared of the scary Atrocious Pokémon. When Ash tried to use his Fearow it turned out to be sleeping. Next Ash tried to use Pidgeotto, but it wasn't inside of its Poké Ball, having only left behind a note to explain its absence. Ash's only choice left was Metapod, which could do nothing but use Harden. For a moment it looked like Ash had lost but then his Metapod evolved into Butterfree. Seeing his chance, Ash had Butterfree use Sleep Powder on Gyarados, putting the huge Pokémon into sleep.
Misty's Gyarados, who was nicknamed Gyara, first appeared in Gyarados Splashes In!. It was stolen and used for experiments by Team Rocket, causing it to go berserk and attack Misty. Then Red appeared, recaptured Gyarados and returned it to her. Later, in You Know...Articuno!, Red tried to get the HM for Surf but it was accidentally destroyed, so Misty offered to trade Gyara with Red's Krabby, because Gyara already knew that move. Since then, Gyara has been one of Red's main team members.
In the Pokémon Zensho manga
Magikarp in Pokémon Zensho
Misty's Magikarp appeared in Cerulean City where it was seen in her Gym.
Related cards Cards listed with a blue background are only legal to use in the current Expanded format. Cards listed with a silver background are legal to use in both the current Standard and Expanded formats.