Squirtle is immature and fun loving, whose personality contrasts with its best friend, Bulbasaur, who is the serious and mature one. Despite this, Squirtle is a capable leader when it was part of the Squirtle Squad.
In Beach Blank-Out Blastoise, Squirtle, alongside a wild Wartortle, led the other Squirtle and Wartortle in the Island of Turtle Pokémon to save a Gyarados submarine powered up by Team Rocket and later being teamed up with its king, Blastoise, to blast them back to the ocean with their Water Gun and Hydro Pump combination.
In The Pokémon Water War and The Fire-ing Squad!, Squirtle gains a friendly rivalry to Aidan's Wartortle in terms of fighting fires and being capable in leading their respective groups. Their initial meeting was awkward at first, especially when they were competing with each other, until both gained their friendship and respect after they are captured, including Pikachu, by Team Rocket, and saving the life of a young boy from a burning building. This also happens in the Fire and Rescue Grand Prix when both Squirtle and Wartortle finally meet again for the competition. Both are seen commanding their groups to stop fires during target practice, and later during the finals.
In Gathering the Gang of Four!, after reuniting with Ash along with Pikachu, Charizard and its best friend, Bulbasaur, Squirtle also befriends May's Squirtle when they play together upon meeting and it does a playful hug to think it has a little sibling on its own.
Squirtle was the sixth Pokémon Ash caught. Before Ash caught it, it was said to have been abandoned by an unknown trainer along with several other Squirtle, where they eventually formed the Squirtle Squad and it became the leader. It soon took a liking to Ash after he saves it from a bomb attack made by Team Rocket and decided to travel with him as it let its Squirtle Squad stay with the local Officer Jenny as Pokémon firefighters to put out fires for the local town.
Squirtle was one of Ash's most commonly used Pokémon throughout his travels in Kanto and the Orange Islands and proved to be a powerful fighter despite its small size. Squirtle is best friends with Ash's Bulbasaur and, like Bulbasaur, it has shown no interest in evolving despite the fact that it was certainly strong enough to have evolved. Squirtle kept the glasses it had while it was a member of the Squirtle Squad in its shell, but rarely wore them. Squirtle is also used in some occasions to assist other Pokémon such as to stop lit dynamite and cooling them off while they are stopping the lava from flowing.
In Beach Blank-Out Blastoise, Ash was bumped into by a wild Wartortle who needs someone's help as Pikachu could not understand what it says. Pikachu sends Squirtle to come out of Ash's Poke Ball as they converse. Squirtle realizes their problem and he shows his Squirtle Squad glasses to wear them as both turtle Pokémon swims to the island of Turtle Pokémon while Ash and the group followed it in a boat. Ash and the group see all the Squirtle and Wartortle are living in this island and its king, Blastoise, who are all asleep. When Ash tried to hug Blastoise, he ends up falling asleep, even Squirtle as well. Pikachu uses Thunder Shock similar to an alarm clock to wake them up, making Ash and his Squirtle mad and realizing the strange noise they heard is what put them to sleep. When Brock realizes it was Jigglypuff who made everyone go to sleep and was stuck in one of Blastoise's hydro cannons, Team Rocket manage to get it by chance before Jigglypuff manages to Sing them to sleep. Upon the panic of all the Squirtle and Wartortle, Squirtle washes them with Water Gun to stop their panicking and leads them to get Blastoise back from Team Rocket's submarine. They successfully get the submarine back to the surface, retrieving a sleeping Blastoise. Team Rocket later attacks them with their submarine, now with wheels, to capture all of them. All the Squirtle and Wartortle use their Water Guns, but it does not work as it gives chase to capture them. Squirtle and Pikachu tries to wake Blastoise with its Water Gun and Thunder Shock combination and it successfully wakes Blastoise while Jigglypuff was ejected out of its hydro cannon and lands inside Team Rocket's submarine. Blastoise fight off the submarine and it manages to destroy its controls. Squirtle teams up with Wartortle and Blastoise and its inhabitants to wash them with its Water Gun followed by Blastoise's Hydro Pump to send Team Rocket drifting off the ocean before the submarine exploded. Squirtle also saves Jigglypuff from the explosion of the submarine before it sings them to sleep. Afterwards, they woke up with black mark sketches made by Jigglypuff after it was offended again by having it's audience fall asleep during its song, and everyone gives a hearty laugh. They happily bid farewell to Ash and his group as they travel back to Viridian City.
In The Pokémon Water War, Squirtle teams up with Staryu to stop the fire, but it is not enough until the arrival of Aidan and his Team Wartortle, who manage to stop the fire. Aidan's Wartortle, which is the leader of the team, has an initial rivalry with Squirtle after it became disappointed for losing its pride as a firefighting Pokémon. It's rivalry later subsides during Team Wartortle's training session and its capture by Team Rocket, including Pikachu. Both Squirtle and Wartortle manage to flood the cabin with its Water Gun to put Jessie, James and Meowth in its collision course. When Meowth attempts to use Scratch on them, Squirtle and Team Wartortle uses Withdraw as his scratch attack cuts through the net. Afterwards, Team Rocket is blasted off by Team Wartortle and Squirtle's Water Gun, followed by Pikachu's Thunderbolt. They arrive at the burning building where the kid was trapped. Both Squirtle and Wartortle are being lifted up by Aidan's Blastoise to save the kid from the burning building using its Hydro Pump. Squirtle manages to save Wartortle from falling while the latter is saved by it from a falling burned door by destroying it with its Water Gun. Both Pokémon are seen safe with minor injuries while Wartortle carries the kid to safety. After the incident, Squirtle and Wartortle finally shake hands showing their friendship and respect with one another before Ash, Misty, and Tracey part ways with Aidan and his team.
Squirtle also battled against the Orange Islands Champion, Drake. It was squeezed by Bind, but used Hydro Pump to break free and finished it off with Skull Bash. In Enter The Dragonite, it fought Dragonite, only for its Hydro Pump to be countered by Dragonite's Water Gun. Squirtle was able to use Withdraw to endure most of the following Thunderbolt, but was still badly hurt. Squirtle used Bubble to hit Dragonite dead-on, but the attack was only half successful, and it was beaten by a Slam attack from Dragonite's tail.
Shortly after their adventures in the Orange Islands, in the episode The Fire-ing Squad!, Squirtle reunites with its Squirtle Squad led by Officer Jenny, and Aidan with his group of Team Wartortle. Both groups are entering the Fire and Rescue Grand Prix, which Aidan's group is the current champion. During target practice, Squirtle sees its squad has a lack of practice and in its nervousness, it angrily manages to step on their tails with its foot to focus on the target. After that, Brock comments that Squirtle can lead his squad to win the Grand Prix. When Ash and the group are easily eliminated in the competition, they cheer for the Squirtle Squad, but they don't listen to Officer Jenny's commands. Pikachu gives them attention with its Thunder Shock as Ash tells them to follow their leader and convinces Squirtle to help its squad, which it succeeds at until it was interrupted by a giant robot led by Team Rocket, which is manned by Jessie, James and Meowth. They threaten the area with their flamethrowers, causing Aidan and his Wartortle group retaliate, but the robot extinguish their Water Gun. As Pikachu and all of the Water-type Pokémon from the competition are captured, this makes Squirtle and its Squad revert to doing their old troublemaking antics and this time it is against the robot manned by Team Rocket, who is finally knocked down with their teamwork. Squirtle manages to break through the robot's face with Skull Bash while knocking the trio out with its Water Gun, as it destroys most of its controls while they are inside and manages to release Pikachu and all of the Water-type Pokémon competitors in captivity, eventually blasting Team Rocket and its robot off with Water Gun along with Pikachu's Thunderbolt. Ash finally convinces Squirtle to help its Squirtle Squad to stop fires as the competition is now resumed after the incident. Both Team Wartortle and the Squirtle Squad are now in the finals as both had a tough time clearing up the fires and rescue the victim inside the fire. The Squirtle Squad manages to win the competition, beating Team Wartortle in one minute and two seconds to stop the fire. Aidan congratulates Officer Jenny for the win. After the competition, Ash allows Squirtle to go with the Squirtle Squad and Officer Jenny as it gives a farewell to Ash's Cyndaquil, Pikachu, Chikorita, and its best friend, Bulbasaur, who turned away and uses its vines to shake its friend's hand, as it was saddened to see his friend go as Squirtle and the squad ride off with Officer Jenny's motorcycle as Ash remembers the time Squirtle joined his team and its battles in the Kanto region and having a good time partying in Pallet Town. With that, Ash and the group watch Squirtle and its Squirtle Squad ride away.
Squirtle returned with Ash during the Silver Conference and Officer Jenny tells him that Squirtle was given time off from its Squad just to compete in the Silver Conference and Ash excitedly registers it to replace his injured Kingler, who is currently being treated in the Pokémon Center. Ash battles Macy in the Silver Conference using Squirtle as his last Pokémon, defeating Macy's Electabuzz and Quilava. After that, Ash allows it to go with its best friend Bulbasaur to spend time and play together which both wanted to come with them.
Squirtle has a bitter rivalry towards Jackson's Azumarill after it throws half of its apple on its head as Bulbasaur tries to restrain them both from fighting until Jackson's Meganium join the fray by tripping Bulbasaur's leg up with its Vine Whip, causing the latter to get angry. Both Ash and Jackson's Pokémon almost had a brawl until Harrison's Miltank manage to calm them down with its Heal Bell.
Squirtle's latest appearance was when it joined Ash's team, along with Bulbasaur and Charizard, in order to battle against Pyramid King Brandon. Squirtle also befriends May's Squirtle upon meeting it, and they briefly play together, with Squirtle doing a playful hug towards May's due to its small size thinking it has a little sibling on its own.
During Ash's training camp, Squirtle becomes mad when Charizard is causing mischief, but their constant fight causing Pikachu to angrily shock them, including Ash, with its Thunderbolt after Bulbasaur hits it with its Razor Leaf which is supposed to be ineffective to Charizard. During the camp fire, Ash also reminisces Squirtle and his Squad as he encounters them in their journey as troublemakers. But after he saves them from a bomb attack by Team Rocket, they are later became firefighters to stop fires. Squirtle along with Bulbasaur, Pikachu and Charizard are seen training with Ash and also practices his newly learned Rapid Spin. When Pikachu was captured by Team Rocket, Ash along with Bulbasaur and Squirtle are mounted on Charizard to pursue the steel-type Meowth Balloon. Bulbasaur, Charizard and Squirtle did their best to stop the steel balloon but it doesn't work until both Charizard and Squirtle combine with their abilities to make a crack on the balloon allowing Bulbasaur to destroy it with Razor Leaf to make them fall into the ground. Team Rocket eventually blasted off by Pikachu's Thunderbolt, Squirtle's Water Gun, Bulbasaur's Razor Leaf and Charizard's Flamethrower. Brandon arrives to see Ash as Charizard senses his presence, he became impressed to see them battling against Team Rocket. Ash becomes excited when he heard his assistant told him that he had found the Pokémon he was looking for which Brandon knows. He suggested to make their battle in a 4 on 4 so that he needs to know more of four of Ash's Pokémon which Ash accepts his offer.
In the Battle Pyramid, after Bulbasaur defeats Brandon's Dusclops, who manages to bring Charizard down, Squirtle fights off against Brandon's Ninjask and managed to defeat it with Skull Bash, but is defeated by Solrock from its Solar Beam. After the battle, and Ash gains the Brave symbol, Squirtle is last seen riding away with Officer Jenny to return to its Squad and has not been used since.
Squirtle makes a brief cameo in Alola, Kanto!, where Rotom Pokédex is taking pictures with its Squad while in a fire-fighting uniform. This indicates that Squirtle is now resided at Professor Oak's lab along with its Squad and its best friend Bulbasaur, who serves as a peacemaker at the lab.
|Water Gun +||Here Comes the Squirtle Squad|
|Skull Bash +||The Kangaskhan Kid|
|Tackle||The Misty Mermaid|
|Bubble Beam||Mewtwo Strikes Back|
|Withdraw||Fire and Ice|
|Hydro Pump +||Misty Meets Her Match|
|Bubble||Enter The Dragonite|
|Rapid Spin +||Gathering The Gang Of Four!|
|+ indicates this Pokémon used this move recently.*|
- indicates this Pokémon normally can't use this move.
Voice actresses and actor
- Ash initially wanted a Squirtle as his first Pokémon.
- Squirtle is Ash's first Pokémon to have a trademark item; its sunglasses. Sceptile, during all of its evolutionary phases has a twig in its mouth. The third, Krookodile, coincidentally also wears sunglasses.
- Squirtle knew Bite In Island of the Giant Pokémon!, which was the only time used it.
- Even though Squirtle was seen at Professor Oak's lab in the opening titles of Pokémon BW: Adventures in Unova, it (along with Primeape) wasn't present in the photo seen at the end of the Best Wishes! series of Ash and all of his Pokémon, making it the only member of Ash's original team who didn't return in the Best Wishes series.