I play PT fairly well. Not as good the PT mainers but good enough to beat alot of the people i play online. As for fighting squirtle hes fast and hes pretty evil at times. Against a good one you constantly have to be on ur guard against his quick aerial movements and trick ground style.
If hes really aerial, you can try focusing on shield grabbing to do your majority of ur damage. Lots of retreating tactics and space as quickly as possible. Attacks that hit multiple times would work best against a squirtle, like nair, uair, or side special in the air. If ur good at ART tech, it will greatly help here, atleast defensively.
Against a grounded squirtle, maybe wing dashing would help against him. To help avoid the hydroplaining or pivot smashes/grabs. Arrows might not be too useful against a grounded squirtle, tiny and fast moving, it might be hard to aim at him. Once again multi hitting attacks work great against really fast characters. Infinite jab>dtilt/fsmash will work great against the squirtle if he doesnt get knocked away by it.
For offensive, i would say the best bet would be to knock him up. Now i know u may think thats stupid because its squirtles territory, but pits uair has really good priority, so if u can stay below him you have a pretty good chance of give him some damage. Good ways to knock him up would be Dash attack, dtilt, dthrow, uthrow, and utilt(maybe kinda dangerous, it takes a while to finish and ur completely stationary.) And seeing as uair will probably knock him away, its always nice to try and follow up with an arrow as soon as you can release one. It will give each of ur combos an additional 3-5% damage when you can hit your target.
When ur at higher% dont let urself be grabbed by him or ur dead, u have to watch from around 100-120% ish, where he can instantly kill u with a dthrow. Dair is also something u want to watch out for, has some huge horizontal knockback.
While they are attempting to recover, best bet would be to chase them down with wing renewal. Arrows will be rather hard to aim at such a tiny object and his recovery is pretty decent, so u cant expect a squirtle to die from not being able to get back. Mirror shielding him is also a possibility but doing it offstage is essential, squirtle is really easy to sweet spot the ledge so dont expect him to over shoot it either.
If he uses withdraw to recover, its best to try to hit him anyway and send him in the other direction, its always good to follow him a bit after you hit him, cause chances are he will still make it back, and theres a bit lag after he cancels the move. If he does it while on ground go for a foot stool if you can to leave him completely vulnerable. If you can shield or spot dodge it and chase him down. He will need to stop and when he does hes left open for a second, good time for punishment.
Watergun shouldnt really bother pit, just remember he has it if he charges it. But theres only a small chance it can actually do anything to pit.
Thats all i can really think of ATM. I hope it helps some.
