Okay, I'm watching the first match.
You roll a lot... you don't really get punished that much for it at the moment, but it's just something to watch for.
If they're on the ground, it's fine to run over to them, but... at least face them. If your back is to them, you can't shield grab the get up attack. I guess you could shield it, wavedash out of shield and then grab, but why waste the effort?
Use your invincibility frames to ledge hop attacks. I can't emphasize this enough. When you ledge hop, you're using up your double jump, so you REALLY don't want to get hit out of it. Ledge stall or something first, make sure you have you invincibility frames, THEN ledge hop.
Also, as cool and useful as the ledge hop nair is, keep in mind that there's other stuff you can ledge hop that works better in other situations. Like your first one probably should've been a uair. And for reaching further into the stage, I like fairs. But that's my preference. Uair advice still stands, by the way.
Good jab against the Illusion, and good thinking with the Counter, but you should really either drop and hit him with a fair while he's charging the Fire Fox or grab the edge and hit him with a dair/bair when he comes back up. Then you won't have to deal with ledge techs and such.
Wow. Good reaction against the second Illusion. But still, he shoulda been dead already =P
Um. lolwut? Either way, you should try to go for something like a ledge dash grab or just get up grab. Nair won't help you much, since it won't send him off the other side of the stage, and really, just tacks on a little more damage whereas you could be edge guarding.
Stop killing yourself.
After hitting with a fair at low/medium percentages, you should be able to grab. Grabs against Fox are good.
Yeah, that's how you edge guard Fox. Stick it to him! Just don't get hit next time =P You don't have to go out that far, just put yourself in a position where he can't get past you. You have a sword, use it!
You play a little too defensively. Shield less, roll less and put on more pressure. Dash dance where you're shielding/rolling and you'll be much more in control of the match.
Wavedashes are cool, but Marth has a pretty long dash dance. So just dash dance grab. It's faster at the distances you're using it at and it's more adaptable.
Good try with the tech read, but even if he had rolled in the right way... he's at twelve. You're not going to kill him with an fsmash, fully charged, tippered, whatever. Dash dance around and try to get another grab him. Tech chasing is fairly easy near the ledge.
Looks like you got nervous on that last stock. Don't. Just play it like you did the whole game (minus the suicides) and don't look for the kill earlier than you can get it.