Squirtle is the first, and arguably the most popular (or equally popular with Blastoise) of turtle pokemon, and as such, one of the Kanto starters appeared many times in the series. Below is a list of episodes featuring Squirtle, others than the Ash’s, May’s and Tierro’s.
Below is a list of episodes in which this Pokemon appears – the first number is the overall episode number, the second is the episode number within the sub-series, AG is Advanced Generation, DP is Diamond & Pearl, BW is Black & White, SM is Sun & Moon , PK stands for a special episode (focusing on Pikachu) and PO is Pokemon Origins. Episode numbers according to the Bulbapedia.
001 – Pokémon – I Choose You! – Squirtle appears in Professor Oak’s show Ash is watching. And in Ash’sdreams. And it’s Squirtle that Ash tries to pick as his starter, but “someone” (Gary) beat him and already chose that turtle.
012 – Here Comes the Squirtle Squad – Squirtle Squad appears.
015 – Battle Aboard the St. Anne – Squirtle figures and T-shirt appears, one trainer boasts about his Squirtle (saying that he has a hard shell), another one uses his Squirtle in the fight against the Team Rocket.
028 – Pokémon Fashion Flash – You can see a various Squirtle, including one with a haircut done by Team Rocket and one with glasses.
052 – Princess vs. Princess – Only as a doll.
056 – The Ultimate Test – As part of the tests/exams, Nurse Joy fights with assigned Squirtle.
060 – Beach Blank-Out Blastoise – Episode filled with Squirtle, Wartortle, one Blastoise, also an island that resembles a turtle shell. There’s also Ash’s Squirtle in this episode, of course.
080 – Friends to the End – Ash’s Squirtle is seen a few times in the episode, and some other Squirtle is seen walking by some trainer during the parade at the end.
091 – Bye Bye Psyduck – Besides Ash’s Squirtle, you can also see some Squirtle in Marina’s dreams-thoughts.
097 – The Crystal Onix – One of the smashed crystal statues looks like a Squirtle.
106 – The Pokémon Water War – Besides Ash’s Squirtle, a whole group of Squirtle firefighters appears (there are also Wartortle and Blastoise teams).
117 – Don’t Touch That ‘dile – Some Squirtle in Flashback. There’s also Ash’s Squirtle.
147 – The Fire-ing Squad! – Squirtle Squad reappears! And Ash’s Squirtle, of course.
158 – A Goldenrod Opportunity – Squirtle appears as a puzzle in “Who’s That Pokémon?”.
162 – Type Casting – Squirtle appears in the form of a sprinkler/watering can.
170 – A Better Pill to Swallow – Squirtle is shown as a visualization of what the old man says about his medications.
216 – Dueling Heroes – Some trainer’s Squirtle has a minimal part in an episode, he is visible with him in the background in one scene.
289 – AG015 – Gonna Rule The School! – Squirtle is shown when the training room is shown. Wartortle is also seen in this episode.
345 – AG071 – A Six Pack Attack! – Oak brought with him Kanto starters, including of course Squirtle, he appears throughout the episode.
348 – AD074 – Hokey Poké Balls! – Squirtle appears as a puzzle in “Who’s That Pokémon?”.
376 – AG102 – Where’s Armaldo? – The quiz asks about starter that Ash wanted to chose (his first pick was Squirtle).
463 – AG189 – Gathering the Gang of Four! – Squirtle Squad in Flashbacks.
488 – DP022 – Borrowing on Bad Faith! – You can see Squirtle of some trainer taking part in the competition.
615 – DP149 – Sticking With Who You Know! – Someone’s Squirtle shows up, he is in love with Raichu (as a result of the work of a certain machine, which is the main plot of the episode).
773 – BW116 – The Fires of a Red-Hot Reunion! – At the beginning, the Kanto starters are shown in form of big ornaments. Then Squirtle with the other Kanto starters is shown on the screen with Professor Oak and Tracy.
791 – BW134 – The Journalist from Another Region! – You can see a Squirtle on the cover of the magazine (Turtwig, Grotle and Torterra are also showed inside).
815 – XY016 – A Jolting Switcheroo! – Squirtle appears as a mascot in the shop window.
838 – XY039 – Summer of Discovery! – Squirtle appears as a puzzle in “Who’s That Pokémon?”. Also, Tierro’s Squirtle is in the episode.
942 – SM003 – Loading the Dex! – When images of Pokémon are showed in Rotomdex, the shadow/outline of Squirtle is visible.
959 – SM020 – Partner Promises! – On the tables you can see Pokemon-inspired treats, one of them resembles a Squirtle shell.
963 – SM024 – Alolan Open House! – You can see a Squirtle figure on one of the tables.
1086 – JN001 – Enter Pikachu! – Squirtle is visible on the poster, there is also a Squirtle in person.
1087 – JN002 – Legend? Go! Friends? Go! – Squirtle is visible on the poster, Blastoise can be seen in the photo in the presentation. In person, Squirtle and Wartortle are seen in this episode.
1088 – JN003 – Ivysaur’s Mysterious Tower! – Squirtle of some trainer is visible in one shot.
1106 – JN021 – Caring for a Mystery! – Squirtle is visible on the photo.
1128 – JN043 – Sword and Shield: The Darkest Day! – The outline of Gigantamax Drednaw appears.
1143 – JN058 – A Rollicking Roll… Eyes on the Goal! – An episode whose second section is completely turtle, with all the Poke-turtles appearing in it (existing at the moment of the episode’s premiere, of course), including Squirtle. We have screenshots from this episode separately, in this note.
1166 – JN081 – Mad About Blue! – Squirtle appears, two are in the photo and one appears in person.
1202 – JN117 – The Fiery Road to Mastership! – Squirtle appears, held by his trainer.
1221 – JN136 – This Could be the Start of Something Big! – Squirtle, Wartortle and Blastoise appears. Wartortle and Blastoise are with some trainer, Squirtle is with Oak.
1222 – JN137 – The Road Most Traveled! – Delia uses the Squirtle shaped watering can.
1232 – JN147 – The Rainbow and the Pokémon Master! – There is Squirtle (the starter Pokémon) on the poster and in person, with the other starters.
PO01 – File 1: Red – Red’s rival, choosing Squirtle as his starter, appears in several scenes in the episode.
PK24 – Meloetta’s Moonlight Serenade – Squirtle have a lot of scenes here. Turtwig also appears.
SS014 – Journey to the Starting Line! – Kanto starters play important roles in the episode, so of course Squirtle has some great scenes for himself.
Pichu Bros. in Party Panic – The Squirtle Squad (three regular members, without Ash`s Squirtle) appears.
SS006-07 – Of Meowth and Pokémon – Squirtle Squad appears.
SS019 – Pokémon Mystery Dungeon: Team Go-Getters Out of the Gate! – Squirtle is the main character of this episode.
M01 – Pokémon: The First Movie – Mewtwo Strikes Back – SquirtleTwo appears.
Movie TV special 1 – Pokémon: Mewtwo Returns – BlastoiseTwo and SquirtleTwo appears.
Pokémon: Mewtwo Strikes Back – Evolution