Okay.
I'll start with standard moves. Her Jab is pretty meh in this match up. If you try to Jab > Grab you can just double Jab between it. Most of the time when I get Jabed I just Jab back, it always works. Her aerials can be a little annoying because they're all so annoying with good priority. Her Dair isnt really a threat in this match up, Nair or Bair OoS works very nicely. Also Utilt OoS can work. Her Fair is pretty meh. If she's constantly autocanceling Fairs rapidly just camp with Turnips and take it from there. Nothing much to say about the other aerials... Her tilts are pretty good. Ftilt and Utilt have very nice range. Her specials are meh also. Turnips are pretty easy to avoid due to their slowness, and the arc they are thrown at. For stitchfaces, your best bet is to sheild since it immediately makes it go away. Although it does make you have a bit more sheild stun than the others. Bombs are dangerous, they can takea stock from you just like that. If she happens to pull one just try your best to be evasive. If she throws it down from below you can blow it up and not be damaged with Utilt., I think sheilding would be good her too. Beamswords were never really a threat to me. Imo they're the worst item, the can EASILY backfire. If you pull one ust keep glide tossing it. I like to glide toss down since it gets a little bounce to it and makes it harder to catch. Mr.Saturns arent much of a problem, just dont sheild. They can break your sheild sometimes. I like pulling these, they get in the way a lot, start combos, and have nice hitstun. Watch out for Toad when playing her aggressively. When she's recovering, its nice to float out and gimp her since she doesnt have a spike. What I love to do if she's recovering completely horizontally in my range I like to Peach Bomber. It has terrific knockback and has a nice little semi spike to it sometimes. Peach's ledge options are pretty poor. When she's on the ledge I like to keep autocanceling Fairs.
All in all its even obviously. The player with more skill mostly wins. That is of course if they dont pull a Bomb : p