I have some basic knowledge on Peach. One thing I know is she is a character with a lot of potential, due to her ability of floating (like in Melee) Now, I don't play on very high level play, but this has worked for me. It can at least get you started.
One true combo she has is down-throw -> back-air on most, if not all, characters around the 20%-40% area. Depending on their size you can do this a bit later than 40%. If they're at 0%, you can go for down-throw -> forward-tilt.
Down-air while floating, like in all games, is a nice approach option, can rack up damage, and even lead to other aerials like neutral-air and forward-air in some cases depending on how they DI.
Like in Melee, holding a turnip can create a bit of a pressure scenario. Stitchface, Bob-omb, and Mr. Saturn all return as possible picks, and are about as likely to pull as in Melee (though haven't looked up for sure). Mr. Saturn is (IMO) better to pull than the other rare picks as it breaks shields. This limits the opponent's options of dealing with it as you continuously chuck it at them. Usually they'll let it hit them, which then gives you an opportunity to dash attack them.
An advantage of Peach is unpredictability as she has many options with floating and turnip picking. Since she's not exactly high-tier, many people haven't really played against her, giving you more of an opportunity to surprise them. She's a character that could very well grow with time as people discover more about her due to her aforementioned potential.
One disadvantage would be her light weight. While floating you are obviously left open for an unfortunate smash attack if caught at the wrong time. She's also been called one of the hardest characters in the game to master, as there are Peach-specific tricks. I'm sure you'll find some here in the threads.
Hope this helped, at least a little.
