Ok, I watched the Yoshi vid and have some advice for you
You've got a bit of an aggression problem. You seem to be constantly on the aggressive, never on the defensive (something I have been guilty of in the past). The problem is that you predictably
always DI towards the opponent, and he keeps sandbagging you/tossing you around and landing combos early on.
You have another problem that I suffered from prior to about a month ago when I really concentrated on changing my playstyle around and learning new concepts. When you're going for a Fair, you simply...try to land a Fair. Several times in the video, I see you either try to throw a Fair out when he's in your face (too close, he hits you first), or throw a fair close to ground and get hit with lag upon landing.
First concept to work on: punishment.
It's not always about you trying to land hits on your opponent. Often, it is good to move away from your opponent and land an attack to punish them for trying to hit you. This will cause them to shy off and break up their combos.
Attacks that work good for punishing in the air are Nair and Bair, because they come out so fast. You can move away from your opponent's attack and then move back into them with bair for example, or if your opponent rushes an approach on you you can hit them with Nair first.
On the ground, I think Ftilt and Utilt are Peach's best punishing moves. Or, spot dodge and Dsmash (which I think I saw you do).
Concept #2 and 3: Spacing and Autocancelling.
Don't randomly throw attacks out. You'll discover with testing that if you land at the end of the Fair animation, you will land with no lag, while if you land early in the fair animation, Peach will land funny and slow down for a second. This is called autocancelling- the attacks cancel if you land during certain animation frames.
Learning to time your Fairs with float or falling from the right height so that when you touch the ground there is no lag is a HUGE benefit to your game. You can roll away the instant you hit the ground to avoid being punished if your opponent shields or dodges it, or you can grab them or slap them immediately or pull a turnip faster.
Spacing is also critical. If you hit someone at point blank with Fair and they shield, they can immediately grab you out of shield. Before I started really learning to space well, my rival realized that I would always dive in too deep with Fair and started shielding and grabbing me EVERY TIME. Now, I both space and autocancel, so the fair lands with the tip and I'm too far away for my opponent to grab me, and because of the autocancel I can react and roll away faster than he can attack me.
Learning spacing and autocancelling timing is NOT easy and requires a lot of practice but will make a huge difference in your game! I recommend studying Edrees' videos against Marth's and Futile's Wario. They helped me a lot.
Peach is one of the best spacing characters in the game in my opinion, because the float and the tiny second jump let you position yourself exactly where you want to be. Learn spacing and you will be much more powerful, and learn autocancelling and you'll react much faster. When you watch pro Peach players like Edrees play, you'll initially wonder how they react so fast- they seem to land and then be doing something else instantly- and autocancelling is the answer.
Hope this helps! Keep up the good work
EDIT: Just watched the Wolf video. Some of the same problems, but dang I have to say you've got some nice combos ^_^ You seem really in control when you're on the aggressive and hitting him. Very impressive.
The real problem I see is the defensive game. You keep trying to respond to his aggression by trying to hit him back with Fairs, but with you and him both moving at each other he keeps hitting first.
I think your defensive game is where you need to focus, as your aggressive game is very good, you just get sandbagged once he gets the lead on you.
Very nice Peach!
