Well first I want to say that you do a ton of really good things. You are very patient which is good and your fundamentals go along with your patient game. With that being said, there are a ton of things you can improve on.
Fox: This can be said for all of your games, but this was the first match so I will just say it now, you go in end up getting hit a lot. You need to stand back even more than you already do and always have a bomb in your hand. Bombs are your best tactic in general to land damage on the enemy and combo off of. Very few Young links dont use bombs in neutral (Axe) and even he takes them out once they are near death percent for a bomb>dair.
If you find your self in a situation where you dont have a bomb and the fox wont give you the chance to pull out a bomb, you can wall him out with sh fairs until he either backs off or makes a mistake and makes an unsafe approach where you can just nair him.
Speaking of your nairs, you are missing your l cancels with the nairs and it is slowing you down big time so I would recommend becoming more comfortable with nairs and learning how to do late nairs, and cross up nairs and all that good stuff.
Another thing is you use d tilt way too much in neutral. Ill be honest and say that you have found some application for it as a combo extender but for the most part I would use d smash as it comes out faster and has the multiple hitboxes to cover you.
Your edge guards are decent, but I would recommend to not use your boomrang as much. Its good when you see it coming, but when you over use the boomrang you end up missing other chances because of the lag. Recently I have found that d smash covers the illusion to the lede and jab covers illusion to stage. Other than that, you have go fundamentals.
Falco: even more than fox, you NEED bombs ALWAYS. Falco will beat you in neutral every time so you need to realize you wont win and you need to be more patient.
With bombs, you can force falco into apporaching and then bomb drop Oos (it takes 4 frames) and can stun falco long enough to allow you to run away and get more bombs. The more you run away, the more frustrated they get. The more frustrated they get, the more openings you will get. Yeah?
The best way to combo falco is to force him onto a platform and when they start to dair you can just beat them with your u air. And once youland an u air, you can read their techs on platforms and keep landing u air strings.
Again, when you dont have a bomb, you can mix up with fairs and nairs, but dont get too greedy because a single laser and knock you out of your approach.
With fast fallers I recommend you d throw them (when you land a grab) 0-45% and then up throw 46-132% and the d throw from then on. With the up throw at mid to high percents, if you read their DI you can get a free nair and most liekly knock them onto a platform or off stage and set yourself up for an edge gaurd. At really high percents you can just read the tech in place with a dmash or just dash attack.
Marth: The marth player you played was not good at all imo. He dropped way too many easy edgeguards that you gave him. A better marth will d tilt and f smash you and kill you easily so you need to space your recoveries better and mix them up (although you boomrang jumps are very good).
You need to use bomb dair on marth at high percents, and dont edge gaurd with d smash. you f tilt as it has better range and will give you better success.
bombs in general are good against marth as marth is really bad in his shield. I would recommend apporaching a safe distance from his shield grab and then double jabbing to nair. It wont take a lot to pressure him into rolling or jumping Oos shield and I truely believe this is the best way to beat a higher level marth.