Pretty good stuff there. I like your technical game. I'd suggest abusing your b-air more. It's probably her best move and generally has high priority, and when you're in the air it rules the day. At the beginning your pressure game was pretty good, but it slipped as the match went on (it seemed). Anyway, you should use needles more. It's one of the best projectiles in the game, and you can use it to benefit yourself a lot more than you do. Whether it's just standing and shooting a charge shot (great for a little extra %) or shooting them down in midair, it works all the time. You should mix it up, too. If you're in the air, you can shoot her and escape, or needle cancel and come down with a fair (or uair if you're close; it's nice to get your opponent into the air). Hope I helped, and keep up the good work.
EDIT: I missed the second video initially. I'll point stuff out as I watch it.
- at mid percents and above, you can't downthrow->upsmash peach. A decent peach player will know how to get out of it, and since its possible, I would go for something quicker like a tilt. I like what you do later on: downthrow->Nair.
- edgeguarding peach can be tricky, but Bair just sends her higher up. Use Fair.
- reverse needle cancel to Bair @ 2:42 ftw
- lol what happened at the end? nice match