Fighting these types of players are frustrating, I mean it doesn't help that it's netplay but still, any advice at all from what anyone can tell from my playstyle?
I can't claim to know a lot about the safest options with Marth and whatever but as someone who plays Falcon and Marth, I just noticed a few things to keep an eye for:
- 0:00-0:20: this is where the game kinda set its patterns I think, with the Falcon being aggressive and you trying to fend him off. While being defensive is a useful tool against combo strong and hard hitters like a Falcon, I think you might have gotten stuck in that mindset TOO much
- in the defensive mindset, you used the rollback option A LOT in neutral, especially right out of shield, so much so that it almost became like a movement option. It may be helpful to rethink what you're going to do after shielding if you haven't been hit. For example, at 1:44, you immediately roll back after getting hit by a punishable dash attack. The better option would have been to drop shield and pivot into an offensive choice like grab. This is one instance where you can see a habit that you NEED to break to be more effective in punishing.
- overall, you should practice more grabbing to punish whiffed attacks, especially against a character who falls fast like Falcon, so the downthrow to up air would most likely work and even if he air dodges it, you can punish the landing. Grabbing overall, mindset-wise, helps in assuming control over your opponent, which really helps momentum. Important thing to note, though, for shield-grabbing falcon is it really only works against certain moves with a lot of lag, so rarely against aerials, since he can jab your shield.
- you rarely used full hop FAir which is one of Marth's best zoning options, even if your opponent rarely leaves the ground. You did use it at 1:23, but too keen on getting a hit afterwards, so you went forwards with another FAir. Usually full hop FAir should be a retreating wall against approaches, so when you jump and use FAir, the advantage is you can come down with either an attack (another FAir, a DAir or NAir) or bait a shield and grab
- the raw Forward Smashes, either out of shield or just as a way to catch him approaching. This is a tactic that may hit and do some damage in the short term, but is neveeeer good for long term. FSmash should always be spaced well, which is hard to do mentally when you use it soo many times. Getting the tipper of FSmash is what you should aim for, rather than racking up damage. The more damage you do with raw FSmashes, it becomes more and more difficult to actually lead into FSmash with other moves like DTilt, and your opponent begins to anticipate the move itself.
- @ 0:31 and 2:02, I see a pattern of you hitting your opponent, having him fall, and then you shielding as you approach. I assume this is a get-up attack read, which is smart but you may be reading based on your past experiences and not your opponent itself, who's never get-up attacked before. This is one of the times where you may be respecting your opponent too much, so the better alternative may be to not predict but look where he goes, and then acting accordingly.
- a nitpicky thing to improve edge-guarding @ 3:42 , everything about the off-stage movement was great EXCEPT you should know Marth's BAir hits way stronger, so a good thing to do is run off stage, quickly tap (on control stick) the side behind you as you jump, allowing you to turn and be facing towards the stage as you jump off, and then BAir. Falcon's recovery is really telegraphed so it was great that you went offstage multiple times to edge guard.
Overall, you still won the game, proving that biding your time and waiting for approaches is one of Marth's key benefits, I think the only problem was the way you zoned out your opponents and some habits.
I turned that off as a casual in Brawl, and I was a child then. 
