Squirtle (Gen 1 - 8):
* Level 1: Tackle
* Level 4: Tail Whip
* Level 7: Bubble
* Level 10: Growl
* Level 13: Withdraw
* Level 16: Water Gun
* Level 19: Quick Attack
* Level 22: Bite
* Level 25: Skull Bash (Gen 1 only)
* Level 28: Hydro Pump (Gen 1 only)
* Level 31: Iron Defense (Gen 2 onwards)
* Level 34: Rain Dance (Gen 3 onwards)
* Level 37: Surf (Gen 3 onwards)
* Level 40: Ice Beam (Gen 4 onwards)
* Level 43: Aura Sphere (Gen 4 onwards)
* Level 46: Aqua Tail (Gen 5 onwards)
* Level 49: Muddy Water (Gen 5 onwards)
* Level 52: Scald (Gen 5 onwards)
* Level 55: Rapid Spin (Gen 6 onwards)
* Level 58: Hydro Cannon (Gen 6 onwards)
* Level 61: Freeze-Dry (Gen 6 onwards)
Note: The moves learned by Squirtle may vary slightly depending on the generation of the game. For example, Squirtle learns Hydro Pump and Skull Bash in Gen 1, but learns Iron Defense, Rain Dance, and Surf in later generations.
If you're playing a specific generation of Pokémon, you can always check the in-game Pokédex or a reliable online resource to confirm which moves Squirtle learns at each level.