Alright. As you know, I'm not good with critiques, but I'll try my best lol.
The first thing I want to point out:
At moments like 0:35, you gotta be really careful. I feel like it's almost never a good idea to commit to a Nair when your opponent is that far away from you. Almost every time I do it against a high level player, they dash away, dash back, then grab (which is what happened in this situation). If you're not sure if your Nair will reach them or not, it's probably best to either double jump away, or just waveland backwards (which I definitely suggest, because many times they will still go for the grab and whiff, giving you a free punish).
0:58 Beautiful tailspike
It looks like you had a pretty tough time getting around Marth's range. Personally I just love to run towards him and shield. Waveshielding is such a powerful tool in this matchup for Pikachu. If you block an (un-tippered) Fsmash, that's a free waveshield -> Usmash. If you block a (non-retreated) Fair, you can usually punish with Uair OOS or waveshield -> Ftilt (which puts you in a good position for a SH Nair approach). There's really not too much Marth can do when you approach with your Shield except for grab, and there's not many follow ups he can do with a grab on Pikachu as long as you DI down/away from him (except on FD. He can Uthrow and juggle you with Uairs/Utilts and it's very difficult to punish that). On any other stage, he'll probably only get like 10 - 15% damage on you from a grab or something, and it's well worth the risk for that. He can gamble a techchase, but Pikachu's tech in place has those extra frames of invincibility, so there's only a 2 frame window that he can grab you. Tech in place -> buffer roll is pretty safe.
In a nutshell, I recommend to use your shield more. I know Pika's shield sux in general, but it's very useful in this matchup. Especially against this Marth, because he seems very Fsmash happy. If you block any of those, it's a free waveshield -> Usmash. Sometimes I make it my goal in this matchup just to anticipate an Fsmash and block it.
Don't be afraid to get grabbed. His followups really aren't as strong against Pikachu as they are against most other characters, and it's worth the gamble from my experience. Also, if you SH towards him and you're not sure if you'll hit him, it might be best to not commit to that approach. Waveland back and see what he does.
Not too sure what other advice to give, because your Pikachu is very good already so I can't say much lol. Keep it up man
