4:51 - nice DI mixup on the f-throw up-throw, you d-tilt after the u-throw, I suggest up-tilt since you could chain that for some early match damage, then as they DI/SDI to either side you can regrab. It's a great damage stacker on fast fallers.
5:08 - There is a way to hydroplane the D-smash out of shellshift across the stage, it's called hydropivot-dsmash. Normal D-smash out of SS is incredibly punishable, especially by a falcon. Falcon is one of squirtle's harder matchups specifically because of his ability to punish and combo with Dair, or in this case, knee. Usually you can get away with whiffs in other MUs, but against a falcon a D-smash whiff is too risky.
5:12 - To escape the ledge you W/draw away, normally pretty safe, but in this specific matchup falcon's runspeed is actually greater than withdraw's speed. Limiting your use of the move in this matchup is important.
// You have a really nice hydro-grab punish game, be careful of your opponent spot-dodging as you come out of shell-shift
5:36 - squirtle has pretty good edgeguards on falcon, here you used bubble, a better option would have been nair, even though the falcon went high and this was probably surprising, starting a nair then fast falling it can cover effectively the entire recovery option for falcon's up-B. the "Fast Fall Shell Wall"
5:46 - lol, he taunted, many people fail to realize how for back squirtle can recover from
//D-smash to short hop Dair is an excellent punish as they come out of shield, this is definitely something that's going in my bag of tricks
6:07 - once again, even though falcon's up-b grab box can be intimidating, running off the ledge into a nair on top of him should send him out an an unrecoverable angle. Bubble, while perhaps a safe edgeguard, is most often ineffective, nair on the otherhand has armor and is safer than many would assume, while also being able to send at a low angle (like bubble) with more knockback
//You get a lot of reward from poking with d-tilt, be wary of making this a habit as crouch canceling can really punish this. I suggest an immediate first jab following d-tilt, even if they CC jab1 can save you with a clank or even throw off their CC allowing for a grab. Obviously falcon's d-tlit is a little slow for a CC option, so in this matchup I think it's pretty safe for squirtle to d-tilt poke.
//While you dair often as your aerial coverage move, not only can an opponent DI/SDI out of it very quickly, but against a fast faller such as captain falcon, up-air chains could stack on a ton of damage if you were to use that instead, or perhaps even as a followup to Dair.
6:55 - while this may just have been tournament nerves, tech chasing using withdraw is usually a bad option and should be avoided
9:20 (second match) - great to see you punish a getup attack with hydro-grab. This is an incredible option, and is perhaps the most potent use of hydrograbbing.
9:28 - Fthrow to Fair. Adding this to my bag of tricks
12:04 - Shades taunt to up-smash kill. Very stylish.
All in all you're shell-shift neutral game is excellent, there are some fast faller specific combos you could do and many of your combo starters are susceptible to CC. I would suggest practicing shell-slinging into aerials as I don't think you ever did it in your matches, a very potent offensive option for squirtle as you play decidedly defensive, so that is likely your greatest course of improvement (check out the advanced techniques thread if you don't know how to shell-sling).