Lol, wow. If I really know ANY matchup within this game, it's between these three characters.
You know the drill (pun intended.) If your tech skill is solid, and I mean NO-FLUKE DEAD-ON solid, then you can play this matchup aggressively. Fox can pillar shields just like Falco with very difficult drillshining and multishines. Waveshines in general are very effective for damage dealing and setting up easy grabs and usmashes. I would recommend usmash over uthrow uair because it's easier and not as escapable. For uthrow uair, you'd have to assume that Peach won't DI out of the combo.
...Otherwise, you'll want to camp this matchup. My tech skill is really good, but not amazingly perfect. It's really hard to pull off that shield pressure the way PC Chris does it in his recent matches with Cort. An aggressive style against Peach means you can easily be punished (to death, for that matter) with a single fluke. Peach has some of the deadliest and most damaging combos that the game has to offer against Fox. If you miss an l-cancel you can be grab combo'd or chain grabbed to death. If you miss a waveshine you can be grabbed/dsmash/whatever other combo Peach does.
Therefore, I think a very effective style can be Masashi-esque. Lots of full jump bairs and nairs to shines to keep her grabs and dsmashes off you. Punish whiffed dsmashes with a drill on top of her head. Quick ftilts outrange her moves. Jab to jc usmash is also really effective for the kill. Full jump uairs are another cool way to kill her, and it is totally safe against shields as long as you l-cancel and shine afterwards.
Play with whatever style you'd like: Fox vs Peach is a close match of consistency and sheer matchup knowledge. I, myself, like to camp. Fox is one of the few characters who can outcamp Peach. Fox is technically harder to play with... which means Peach will make less flukes. Since it's a match of consistency, you want to make less flukes than Peach. Take it slow and calm down if your aggression isn't working.
As for Ice Climbers...
Pressure the hell out of them. That is how can any character can beat IC's.
- fthrow is very handy, especially if you grab them when you know they're gonna shield
- if one is wide open to attack them, take initiative and do as much damage to that ice climber as possible. drill grab uthrow uair, or usmash or whatever. just do a lot of damage OR shine spike if possible.
- always cover your attacks with shines. if they can't shield grab you then you are safe.
- don't miss an l-cancel or you will face a 0-death grab combo much worse than peach can deal. all you can do is pray that the ic doesn't mess up the chain grabs or wobble or whatever.
- hint: you can cc usmash their side-b recovery.
- usmash is your friend. ic's have pretty much zero control in the matchup if they are coming down from above.