The first match on the best:
-Immediately from the beginning you are short hop lasering (which is good), this is a good way to camp Peach and allow her to approach you (which is what you want).
-You start getting too close to her (this is the LAST place you want to be) and start just random single lasering near her. Peach is amazing against Fox up close, you want to stay at a distance and allow her to approach you with a turnip or some sort of dash attack / dair. You should be able to predict most of her approaches and either run away or beat her in the air with your broken *** dair or something.
-Very strong use of back air and followed up airs, nice job on that. Try to keep Peach in the air as much as possible, it's her worst trait.
-You get the first kill with a nice upsmash read. Although you did well on this one, there may be moment where you can't seem to just get the kill. Peach's airdodge is TERRIBLE and she's extremely floaty. A good Peach will not want to stay in the air too much at kill percentages, but if he/she DOES go into the air at 95+% this is a perfect opportunity to just read their landing and put in an upsmash. Her airdodge is absolutely horrendous and you should be able to capitalize on it. If Peach is on the ground and shielding don't try to test her too much, her out of shield game is amazing and you will most likely get punished.
-Immediately after your first kill you should have went to the ledge and started SUPER camping. Don't do this dumb short hop single laser or whatever against Peach, it's honestly not that great. The thing that makes her the most pissed off is just spamming lasers grounded. Keep in mind that she will either have to 1) Shield (which will allow you to approach with a grab or some sort of safe maneuver) or she will 2) Float (this is by far her worst option) you can just predict her and punish.
-Your second stock the short hop laser approach was working pretty well, but you were far too close to Peach (when you were at low percentages). Take into consideration that Peach can put in a **** load of damage extremely quickly while you are on a fresh stock. Although Hero may not improvise on your small mistake, I know other Peach players will.
-Do not shine stall against Peach. Her aerials are wayy too fast and she will just predict you. Find a safe landing and just ... land or try dairing her shield or something.
-Good pressure while Peach is offstage. Do not let her get back on, she's pretty predictable and your fair is really good at pressuring her while she is in the air. Watch out for her fair of course. While you are at kill percentage (meaning YOU are about to die) stay on the ground. If you think about it, the only move Peach will really be killing you with grounded is a Forward Smash or Up Smash, which are both really really hard to land. If you are on your game and staying away and playing careful, Peach should have a hard time killing you.
The First Worst Match:
You didn't play poorly, your recovery was just horrific. Don't ever phantasm onto stage ... especially at mid height against Peach. If anything, do it low so she can't follow up too hard on you if she nairs it. The ledge is always the best option of course, or you can just wait for the platform to come back on Smashville. I'm not going to do a lot of specific stuff on this match because I covered it in your first best match.
Take all of this stuff into consideration when you play Hero next time. You're a pretty good player and I definitely think you can consistently beat him. You just need to think a bit more about what you are during while you are playing and the cause/effect of your actions.
Also, try out Halberd for a counterpick versus Peach - she HATES that stage.
I see you chose Pokemon Stadium One as well as Lylat, both strong choices because Peach is not too great there.
Hope this helps!
Sorry about the delay :'(