plus SHROUDEDONE is gonna come in here and help you out, im sure of it
Are you making fun of me?
Anyways, it's important to know what Peach wants to do vs you:
1) Turnips: She wants these. They give her leverage over you, a decent out of shield option, and force you to approach. So just hang around bairing in a range where you can't get downsmashed/naired/hit by her good close range moves, but where you can start to go on the offensive if she tries to pull a turnip. I'm in favor of being threateningly close to her, but not going full in until she tries to pull a turnip, then going for bairs/grabs. If she pulls a turnip and then shields, always grab her. Uptilting/bairing her shield is bad here because she can throw turnips OoS, and even if you catch an OoS jump with an uptilt, the turnip will sometimes dislodge itself from and hit you, making a followup impossible.
Generally, camping her will only be bad for you. Stay in her face.
2) Shield: She doesn't want to get rested. No one does, really, but Fox/Falcon/Falco/Doc/Marth all have decent punishes on it. Peach does not (I shouldn't tell you this secret, but it's in your best interest to always ban FD vs her). So she's going to be shielding (and crouching) a LOT vs you, so that you can't pop her up via utilts/bairs/uairs into rests or offstage chains. Once you get her in her shield by bairing a bunch, you can start mixing up between late and early aerials on her shield, tomahawk grabs (jump over her shield > grab from behind), tomahawk uptilts. She has some solutions to this, but don't worry about those for now.
For rest combos, just rely on utilt and maybe uairs below 20%. You can CC her dash attack into rest, or rest OoS below about 40-45.
3) Trades: Without rest, you die earlier than she does. You both are really floaty, but she's got weight on her, which helps her live longer. Space bairs and don't let her trade with you. Her fair is really good, if you see her trying to get above you in order to fair, just bair her jump, and bair before fair comes out. If she's bairing to catch your bairs, just time your bairs after hers.
Mahone covered everything else. You probably won't get edgeguarded unless you go low (again, ban FD [unless you really don't like Yoshi's/DL/PS vs her] ), so don't recover to the edge, and you're fine.
To add a bit to what Idea said: Don't shield vs Peach. Never a good idea for you.