I love this guy using 12 year old insults with his tags haha.
Also, I think I figured out what the fundamental thing I've been doing wrong is...
I haven't been looking at the enemy. :/
I've basically been focusing in the neutral space in between the characters, using my peripheral vision to try and see both the opponent and myself, and while it worked well enough for seeing things coming at me, it seems as though my focusing on the stage itself prevented me from being able to think about what the opponent was trying to do. I don't know. But I realized this in a match against a Little Mac, who I very narrowly lost against (I could've sworn you could shield a KO punch...). About halfway through this fight with a Link, I remembered that I should've been fucking GLUING MY EYEBALLS TO HIM instead of just trying to see everything, and I think it turned out quite well:
https://www.youtube.com/watch?v=MQ2pUrD3O-c&feature=youtu.be
*This should work I guess. My first YouTube video*
Good stuff, friend. Yep, you definitely want to focus on the enemy more than yourself; you already know what you're doing, so watch what they're doing and plan accordingly.
I noticed you relied heavily on rolls as a form of movement, something weaker players often do. Use your dashes more, even walk before you think about just rolling to get to where you want to go. You can jump out of them, but not out of rolls so consider your options. The other issue with rolling is if you abuse them like you did in that match, you'll be punished by stronger players when you're vulnerable. Try to curb the habit and explore other options; you have a float, so try it.
Keep track of what turnips you pull and whether you pulled an item. If you got a Mr. Saturn, bait out a shield and break it. If you got a Bob-omb, try to blow them up but don't be hasty. If you get a stitchface turnip, take advantage of its high knockback to send the opponent flying, and so forth. You tended to haphazardly toss veggies without regard to what they were.
When you're looking for the kill, try to make them come to you in your situations. You're Peach, you don't excel in approaching but in punishing approaches. You're not Falcon; throw some veggies at Link and make him feel like he's not gonna kill unless he gets closer, and then dodge his tactics and punish accordingly. Don't be afraid to wait, you still have 2 minutes on the clock, plenty of time to seal the game. You never know if a lucky veggie is right around the corner, so don't just toss out dash attacks hoping they'll stick.
On that note, floating in and out of their space is something to keep in mind. Fair and bair are good tools to lay on the pressure, as well as dair from above and uair from below. Nair should be your combo breaker in the air and something to hit them off-stage with.
As you get used to seeing what your opponent is doing, try busting out the Toad. He's really strong in this game and a well-placed Toad counter can turn the tables in your favor.
Also, I need to get an actual camera or capture card, your video makes mine look like shit. ;__;