Yo! Ok so I watched all of your matches and let me first say that you've come a very long way since the very first clip you ever showed me of your Marth. Ok friend, now for the critique.
First I will talk about your SHFFL game. Your l cancels aren't consecutive enough. It was most noticeable when you did your dairs. Here is what you should do. I'm sure you know/noticed, but the l cancels for your aerials varies due to three possible scenarios. One is when your aerial actual hits your foe, when your aerial doesn't hit anything and when you hit your foe with their sheild up/invulnerable frames. Understanding the timing of these three scenarios will better help you get the timing for l canceling. This comes with time, so fear not. Just keep working on it.
You seem to like double fairs as an approach. I know its sexy but single SHFFL fairs (keep in mind its a good idea to switch the fast falling timing of these) are a much better approach. But fear not, double fairs do have a much better purpose. If you are feeling pressured for whatever reason use retreating double fairs. Its a much better purpose. Its best to C stick both fairs btw so you can hold back on the analog stick.
One major habit that stood out to me was your double jumping. In the first match against Sheik, almost every time she hit you while you was in the air you would double jump right after. The best option is to simply DI away and think about landing back on the ground safely. I'm guessing you're afraid she would hit you, or maybe it was a subconscious thing. Whatever the reason may be, keep in my that sword in Marth's hands is your friend. So instead of double jumping and trying to float back down, just DI away and if need be, grab the edge.
Spacing was another thing to some degree. Your spacing in your last fight was very sexy, whereas in the first few vids it was again...not consecutive enough. I think you understand spacing, so no need to bore you with tips on that, I'm guessing. lol
Now for your overall edge game. I'll start of with your edge guarding. You had no problem getting the Sheik off the stage and you had the whole grab the edge, roll and forward smash thing. But you can take it much further. While Sheik is off the stage I'd recommend you attempt to run off and fair/or even shield breaker (for style points) her while she double jumps. There isn't much she can do about it, except DI really. Also, for speeds sake, when you wavedash off the level to grab the edge you can quickly flick downwards on the analog stick to make Marth grab the edge much much quicker. Doing it this way makes it far less likely Sheik or whoever else will be able to hit you during the actual wavedash off the level. Just a suggestion, but I'll leave that one to you. Ledge hop dair is another thing worth adding in your arsenal of tricks.
Now when you're the one being edge guarded, you can switch it up too. How? Well when your using your forward B to get back to the level and you are below the level you shouldn't be surprised to see Sheik let go of the edge and try to bair you. In some cases, you can anticipate this and use your Up B as an offensive to swat her away. In most cases, this can stage spike your foe. lol Another trick I do is air dodge when I'm recovering from above but...instead of DIing back onto the level, I prefer to fast fall downwards to grab the edge. But that's just me.
So yeah those are the major things I noticed. But as a whole, you're a pretty good Marth. Would like to play you someday. If you take the advice myself and others have provide you with, you should be just fine. All the best dude, and keep smashing. XD
