[color=magenta]No, the only possible thing that I can think of that effects accuracy is the CompoundEyes Ability that a few Pokémon have, which increases a Pokémon's accuracy, and the Hustle ability, which decreases a Pokémon's accuracy, while increasing the power of it's attacks by 50%. There is also the Keen Eye ability, which prevents accuracy loss by moves like Flash, Sand Attack, Mud Slap, etc... as well as the White Smoke and Clear Body abilities which prevent any stat from being lowered. However, Squirtle does not own any of those abilities.
There is one more possibility... Is your Squirtle using a move that doesn't have 100% accuracy, such as Tackle? I believe that Tackle is one of Squirtle's starting moves, so if it is early in your game, and your Squirtle knows Tackle, and you are mainly relying on it, that could be your problem.