A few things, in no particular order:
1) Your recovery could use work. You suicide a couple of times because you quick-attack without skull bashing. As a rule, if you are hit into the magnifying glass on the left or right of the screen, always start with a smashed side-b (in case you don't know, smashing side-b gives more distance, same timing as samus super missiles). The only reason NOT to side-b is if you'll be put into lag in a punishable range, but you want to be as close to the stage as possible without being in that range, so that your mixup of recovering to ledge or deep into the stage is impossible to cover.
2) You approach marth with fullhop jolt quite a few times. Against some characters, this can be okay, and it's a habit I get into as well, but marth has a ton of options that not only clang with jolt, but go through it as well. If you use that approach and marth uses an uptilt or fsmash, you will NEVER be able to punish it because you will still be in lag, and he'll hit if you don't drift back. If you want to use jolt to get him to approach, do it from a safe distance or drift back so he can't just punish your landing.
3) Also against Marth, you should utilt or dsmash after shffling through him instead of uair. You don't have very strong followups from uair, and you're forced to sacrifice your positioning every time to make it back to the ground, even when you hit him. With dsmash (my personal favorite) or utilt (which I've seen Axe use a lot) you pop marth into the air, which is awful for him, and you get either a followup or at least a good chunk of damage, and you can put yourself in center stage or just ground yourself underneath him to make it hard for him to get back to the ground. At higher percents you can uair to nair/bair/dair as a kill setup, but in a general neutral situation, other moves cover you a lot better. 2:17 in the marth video is a great example, you just ff to ground and instantly get put back into pressure. On a related note, if you shffl and miss but you're facing him, you can dtilt and that's also pretty good since it clangs with a lot of his moves, comes out fast, has little lag, a lot of range, etc.
4) Wavedash out of shield! I actually can't do it but I'm working on it because with such a ****ty shieldgrab, pikachu needs it to be able to punish people's smashes on your shield. It's super super important!
5) Smash DI falco's pillar combos. The combo at 1:53 in your match vs FC should not work at all. Just get out of there and get into a recovery situation, he can combo you but he can't edgeguard for ****.
6) This is kind of a personal preference, but I really believe that you should use nair to gimp falco's up-b instead of uair. If you use uair you risk messing up (like you did at the end of the first match against MC), but his recovery is so ****ty that nair will basically always take him low enough that he can't survive, and you don't have to worry about his ring of fire so you can just jump right into him and get him with the strong hit. Of course you can just get better at the spike too, but I don't think it's necessary for falco.
7) I think you overuse jolt to edgeguard falco. It's basically a hard read, and you can just make the same read with a nair or fair or ftilt or whatever. I personally only use it vs spacies if I just hit them all the way across the stage and I don't have time to follow up with anything else, but it seems like it's what you default to. If you're just throwing something out to cover options, I think fair is your best bet. It'll clip his phantasm and his jump and it has good priority and a wide hitbox. You lose both your last stocks against MC with a bad jolt
8) I kind of feel like you never grab in neutral. It's kind of risky with pikachu, but you're letting your opponent get away with shielding right in front of you on quite a few occasions. Definitely something that can get you some mileage with guaranteed upthrow combos on like 90% of chars. (hehe, commentators confirmed this for me after I typed it)
9) Not criticism, but holy **** you can DI sheik's dthrow so ****ing far in PAL LOL I'm moving to australia. I actually have nothing to say about your sheik games cause it looks so different from what I'm used to in the US
I think that's pretty much it, I didn't bother with the G&W set cause I don't exactly know the matchup and it's not as important anyway.
One final thing though, this is kind of a guess, but I think one reason you might be ****ing up your quick-attacks so much is because you're not used to how it feels when you hit someone with it. I don't know if it's just coincidence, but a number of your suicides were when you were going through your opponent with the first angle and then messing up your second one. If I'm right, I think you should practice quick-attacking through a character and getting your angles right. I've spent some time on that and have gotten better at my angles as a result. The easiest setup is just to put a character near the ledge and try QA to the ledge from onstage through them. If you can get that timing consistently I think your QA aim will improve in general.
And just cause I don't wanna end without saying something nice, I like a lot of your onstage followups! It's a weakness of mine so it's hard to critique for me, and you definitely get some good hits regrabs that I don't go for enough. Oh, and of course your shielddrops, though I'm sure you get that compliment like 95 times a day