So there were a bunch of things I noticed throughout the two sets i watched but I'm going to start with the set against fox. You need to pay way more attention to the spacing between the two characters and make better use of your float heights. I see you floating in short hop aerial range way too much when fox is farther away. When youre far away from fox you want to float above the height of their short hop aerials (mostly nair and fair) so they cant just run at you with a short hop aerial whenever. Use a higher float height and then approach them with that so that so theyre forced to commit to a full hop in order to punish you for your float. This limits fox's options to run under you up air, full hop aerials and dashing back to avoid your fair. If he dashes back he concedes stage position and if he approaches you with any of the other options you can stuff it with a fading fair or you can stuff the full hop aerial with a nair or just drop float and try to punish the landing. When you get closer to fox (inside his short hop nair range) is when you want to start using your nair to try to stuff his. When youre grounded try to dash dance in and out of his short hop nair approach. this allows you to react/predict his approach and wd back dsmash/grab/dtilt/dash attack his nair's landing.
Also, you turn your back on fox way too much in neutral game imo. even in the sheik matchup you constantly had your back turned and the only real option you can do out of that is bair.. Im sure you noticed during your set that the sheik was just crouch cancel dtilting most of your approaches. if you see her just doing this just run in and crouch cancel yourself and then downsmash or dtilt after her dtilt. you can cc that until fairly high percents. or just run in dsmash. you should adapt with your approaches to the defensive options that they are using
Another major thing i noticed is that your shield pressure/option coverage when you have fox cornered is pretty random. When you have fox cornered, dont always try to just go in on him. if you always approach him in the corner hell just buffer roll and take stage position from you. dash dance, space nairs and bairs to wall him out and if hes constantly jumping out of the corner you can run up and up air.
As for the trading with falco and fox up b its a matter of spacing.. you want to barely touch them with your bair/drag the hitbox into them as opposed to just putting it out as the up b comes at you. once you hit this bair just grab a turnip, fastfall down and throw it at them then follow up with a float nair if necessary.
Do you have any more specific questions about that stuff?
cc is op against sheik her only real options against it are grab and fair lol