So what are everybody's thoughts on Peach? I feel like I've heard a lot of talk about how she has huge potential/is likely upper-high tier at worst, on top of being good against Rosalina, but I haven't seen her much in tournament and we rarely talk about her.
Honestly she's kind of like Puff in that regard, but I understand that puff just really needs a C-stick.
What's so amazing about Peach, and why haven't we seen many?
Peach is a very well-rounded character in this game. In Brawl, she had very strong combos at low and mid percents and her aerials had non-existing landing lag. These were her two best assets. They got nerfed in Smash 4, mainly because Fair has landing lag now and Dair's knockback has been increased, but to be honest, these traits were crazy. On top of that, in exchange for these strengths she had a very glaring weakness: her killing power was atrocious. Her risk/reward ration was amazing at the start of the match (huge combos of safe attacks) but turned awful as the match progressed since she would hit her opponent from the this side of the stage to the other but they would never die, and instead kill you 50%+ earlier (in cases like Snake even 80-100%... it was pretty crazy).
In Smash 4, almost everything about her is relatively good. Her combo's may have been nerfed, but Dair > Fair is still a solid 26%, leaves opponents in an awful position and works even till mid percents, Dthrow is great since it combo's into Nair/Bair/Uair and Dtilt has hitstun for eternity, among more stuff. Her pressure game is still strong because her floating aerials, turnips and dash attack (which has amazing range and kills) challenge landing opponents. Not to mention her Fair, which you really dont want to get hit by.
Now we're actually talking about her Fair... this move is just golden. Range has been universally reduced in this game but Peach's range is still crazy, and especially Fair is just absolutely ********. It has range from here till Africa, hits on top of her, in front of her and below her, and it can be spaced very effectively using floats and shorthops. It has NO LANDING LAG when done in a shorthop or when autocanceled at the proper time, meaning you can float your Fair, retreat, drop and cancel with out any lag and be perfectly safe. As a finishing touch, this move can kill ridiculouslyearly now... it's amazing how a move with such range and safety is still so powerful. Thanks to Fair's knockback, she can consistently score early kills.
However she doesn't rely on solely Fair. Just like Fair, Bair also has amazing range, especially when done in a shorthop, and it also be autocanceled in a shorthop or in float (it can be autocanceled much earlier than Fair too). Bair is a very strong spacing tool because it is safe and it can be pulled back easily, it's super fast, has great range and decent power. This move beats a lot of other moves. Dair is pretty much the same as Brawl: safe, ridiculous range and combos. Nair is still Nair, being a great OoS option, it's fast with little lag and has hitboxes covering her whole body. Uair has amazing and disjointed range, is also fast and is great for chasing opponents or for landing punishes, It's probably the least used aerial so far though since it's very hard to do effective Uair without a C-stick, since I can barely move while doing my Uair on the 3DS.
Anyway, her aerial game is very strong, consisting of exclusively safe aerials, most of which also come out fast and all of which have great range and outspace a looooot of stuff. Other than her aerials, she still has other safe options like Dtilt and turnips on shield. Peach is probably one of the safest characters in the game. This gives her strong pressure game where she can poke at her opponents effectively and a good approaching game, especially with Float since she can basically choose from which corner she wants to annoy you.
And perhaps the best thing of all now...
no killing problems anymore!! *HALLELUYAH HAAAAALLELUYAH*. Her Fair kills early consistently but she doesn't even have to rely on only one kill move anymore. Her Fsmash kills at LOL percents. Pan kills at like 100%. Racket is more dependent of where you stand since it hits horizontally, but nonetheless kills early, and sometimes they get sent at such a bad angle they will not make it bad at the stage even if they survive. (Unfortunately, I have no C-stick and 3DS controls suck so I'm not using this move too often ;_;.) But even if she doesn't score a very early kill with her Fair, Fsmash or Usmash sweetspot, she'll still be like "lol care I have got a million other reliable moves that kill anyway". Usmash's sourspot is way stronger now and can be used out of shield to kill at like 130/140% percent. Dash attack kills at similar percents. Bthrow kills at similar procent if you standing close to the side, it kills at around 170%from the middle. Some people use UpB at the top of the stage since the it connects reliably now and also kills at aroubd 130%. Bair is also still a reliably killing move, although it kills later than Fair. Her edgeguarding also seems to be pretty good since her recovery has been buffed and floating and turnips helps a lot. (I'm not very good at edgeguarding though so I can't really elaborate on that. Slayerz is really good at it).
However, she does have her weaknesses. Her mobility is somewhat slow, and plucking turnips take long, so she has trouble chasing (camping) opponents, even if she's usually safe. She is floaty and fast fall is also slow, so she is very vulnerable when she tries to land since she is a easy target to hit in the air. She also tends to rely on jumps a lot, which can lead to her being punished for jumping especially by stuff like Sheik or ZSS's Down B (admittedly the better Peach will not do any unsafe jumps so it's a pretty minor 'weakness').
All in all Peach is a very strong well-rounded character with a bunch of fast moves, she is generally safe, has good range, a good projectile, good poking game, good spacing game, good approaching game, kills early, good pressure game, decent combos and with all the options she has, she basically has the whole package EXCEPT for slow moving speed and falling speed. Overall, she is very strong.