yesss
unless I'm missing something cool that I might not know about, I can confidently say I know how to float and do stuff while floating
Good. Getting into float instantly and seamlessly is important with her.
I can dash dance , but I can't wavedash with peach because I keep floating intead Q_Q
what's dash cancelling? Is that the crouching thing?
Learn how to wavedash. It is important. Wavedash out of shield protects you from space animal pressure in a lot of cases and allows you to escape or counterattack. Wavedash back down smash helps make Fox's life just a lil' harder if he thinks he can run in whenever he wants and hit you. Wavedash is no longer optional with this character.
Yup I've been playing smash casually for a good amount of time, so I know the basics like movesets and stuff like second nature.
Excellent.
I know her down smash is good and I use it a lot. And Armada is a cool dude. That's about it I guess :/
Alright then.
Okay, finally gonna reply to this.
Peach floats (and FCs) with Fair and other aerials to control space. She's kind of like Puff in that respect. However, unlike Puff, her ground game is actually respectable too. On the ground, her main ground moves are dash attack, and down smash. Grab and jab are also useful.
Defensively, Peach likes to Nair OOS against low range characters, shield grab misspaced or laggy moves (if she's close enough to do so; Nair OOS also works on a lot of this stuff), dash attack through stuff or on lag, WD back down smash on approaches, crouch cancel weak or medium strength moves (especially misspaced aerials), and float back into aerials on approaches. For more information on "which aerial is correct to use when?", consult
this.
Note: Crouch cancel down smash is not as good as it used to be, as a result of people being generally better nowadays. But it is still very good.
Note: Sidestep down smash is good if you think the opponent is going to grab. However, it is also easy to get predictable with it and form bad habits with it, so use with caution. The same applies to rolling, down smashing on platforms, etc. Try to think of alternatives when you're stuck in shield and other situations, and try to think of why they should work. More options is always better; expand your repertoire. Don't develop bad habits.
Offensively, your goal is mostly to pressure the opponent into a place where they can't run away from you, and then cut off their escape options. If you haven't noticed already, just about every character is faster than Peach. This means it's difficult to approach directly, because efforts to engage like Fox can just be run from. However, if you press them against the edge of the stage, this becomes less of an issue. At that point, they have to go through you, above you, etc. They're sort of forced to interact with you. And if they still refuse to, you have turnips, good priority, a beastly dash attack, and other goodies to threaten them (or even hit them).
For combos, just watch Armada. But the gist of it is that Uair is good and weak aerial --> strong aerial is also good. Dash attack is ridiculous, and WD to position yourself during tech chases is also a great idea. D-tilt is a great launcher if you can figure out how to space it properly.
For character-specific strategies, consult the first page of VaNz's thread. In fact, this discussion should probably move to that thread anyway just 'cuz it impedes on Alan's being fabulous with grimy strategy talk.