Hello Melaf! Weird that I've never heard of you. But that makes our meeting even better! My tag is "A Rookie" and I also main Mario, but I'm from Southern California. Well I critiqued your Grand Finals Set since that's the one you really needed help w/ from what I've read and from what I saw.
@ 01:18 - grab the edge vs Sheik next time. Time it so if she does try to up air w/ her 2nd jump, you'll still have invincibility(but at how low she was you were safe). Have to grab the edge so you can force her on stage to kill her.
@ 01:41 - you could beat almost ANYTHING w/ a great inv. waveland on stage into immediate uptilt. You would've definitely beat her ftilt or dropping down from the platform. Waveland uptilt is a great offensive move to keep your opponent honest and make them think twice. Also, when you got slapped offstage, you should've done an immediate tornado(get close to maximum height) so you can conserve your cape to mix up your recovery better. And remember that recovering low vs Sheik only means you want to eat an inv. bair. So only try to recover high or as quickly as possible. There's one way to truly punish a point-blank dsmash from Sheik. That's SH fair after the first hit makes contact w/ your shield. If you have the concentration and reaction, you can punish it consistently. I still haven't punished it enough, but I'm getting there.
@ 05:49 - the grab you get at you could've definitely hit her if you did it faster and angled it up left. You have to angle it when she gets to around like 115ish%, but it works all the way until about 140%.
At 09:00, you should've done a reverse nair to hit her of stage and rinse repeat. The thing about this MU is, you have to mess her up when she's recovering. If you don't take advantage of her recovery, then you just lost like 33% of the MU. I think you should start to DI towards center stage/no DI at like 80% because it's smarter to take an upair that won't kill, rather than going through a tough recovery, if you can even make it. Try to refrain from doing so much nair approaches, he ended up grabbing you a lot for that.
Things you need to implement more is Crouch Canceling for sure! You didn't do it once, not from what I watched. CC'ing keeps Sheik players honest from hitting you w/ walking ftilts or just anything. You counter it w/ a CC dsmash. This MU is whoever grabs more for the most part. If you don't get grabbed at all for one match, I'll bet money that you'll win that match next time. I know it's a lot to ask for, but you can definitely minimize his grabbing potential by stopping the nair approaches and fishing for moves too much. He started adapting to you fishing, and waited w/ a grab. You should've adapted to him and waited for his shield so you could grab. Not enough grabs unfortunately. Also, whenever he needlestormed, you got hit/grabbed 5/6 times. To avoid that, just roll away from all of that to reset momentum and position. If you can't use dairs because he's reading them, then only use them if you want to challenge him in the air. Either by reacting to one of his jumps or making a good read. You definitely have solid fundamentals/traps/gimps/knowledge. I just think you need to play a little more and wipe off the rust. You seem like a good player to me, but just need to be careful on the grabs, doing the appropritae DI, and not gimped. You shouldn't have agreed to no chainthrowing. There's no benefit for you not chainthrowing. Since it only works until like around 30%. Plus, it's weird that you'd agree to that, she can't even chainthrow you XD Haha. Ever time she grabs you, can upb out or just jump out. But good set! You had the counterpicks down to a tee. But lack of grabs on FD hurt my soul. I think if you don't know how to get in effectively, shoot some fireballs to make them work around it and you can force an opening or better positioning that way. I think you're a lot better than this imo. I can tell you're a formidable foe and I want to see you do better and beat him next time you two play.
To beat her:
-CC(don't need this, but you should try it)
-Grab
-Edgeguard
-A Great Recovery
Here is a video of me vs a well-known, modern Sheik back in Feb this year. See the do's and don't's of my gameplay and see if you can use any of it! Take whatever works! :D
https://www.youtube.com/watch?v=1eWOlv6TY-Y
But he was definitely an inspiration to me. Along w/ Green Mario and Brown Mario. And lately, KoopaTroopa895. You should look him up, he's part of my crew and he's getting better as well! But yeah, your Mario is pretty darn good for being rusty. If you have any more questions, just let me know!