Few has been said about Peach so far. IMO she's a very solid character. Her killing problem has been significantly reduced to the extent I could barely call it a problem anymore. She kills well now with her new Fair and her new Fsmash is also incredibly strong. Her moves also do not stale anymore if she floats so she does not need to worry about that anymore. Her Dair combo ability has been reduced somewhat but she can still almost always combo into a Fair or Bair at low to mid percents (50%). Instead her Dtilt and Dthrow seem much stronger combo tools. Her shield pressure has been weakened due to Fair autocanceling much later and if autocanceled to early, it has some lag, although at the moment this may be conpensated somehow since she can cancel the ending lag of her aerial with DownB turnip throw. I don't know exactly how safe this is yet, but it's definitely a helpful tool. Anyway, I think they have made her more of an all-round character this time since her air combos and shield pressure are not as crazy as before, but as an exchange she kills faster and has a better fastfall to reduce her weaknesses such as killing and recovering from above. On top of that, her strong pressure and punishing game is still in the game and it seems she can also edgeguard pretty decently. She does have some bugs though (which are in her advantage) for example the fact that floating aerials don't stale, or that she can cancels the ending lag of her aerials/air dodge by DownB throwing a turnip or, perhaps worst of all, she can cancel hitstun by throwing the turnip with DownB. These things may be removed in the Wii U version and I am guessing at least the DownB bug will be gone. That means no more lag canceling with DownB turnip throws, sadly.
Zelda is... ehh. I don't really know about her. I don't think she is god awful anymore but I'm not particularly impressed by her either. Her new UpB is great and all, but the first hit is hard to hit with and the second hit is super punishable. Her air game is still pretty weak since her Fair and Bair are not at all reliable. Her Dair has improved a lot, but it doesn't have a lot of horizontal range so spacing it is tricky. Other than that she finally has a good grab which helps a lot and all of her tilts are much better now. Her smashes, on the other hand, actually seem to be nerfed rather than buffed. Fsmash is mostly the same, but Usmash's range is much worse and Dsmash is weaker. Furthermore, Din's Fire still sucks and Phantom isn't super good either. She's also light and laggy and not particularly evasive so she won't live very long either (but at least she can recover now!) and her aproaching game is still weak, although perhaps a bit buffed because the game allows you to do titls and smashes easier out of a dash, plus she can actually utilize her grab now. All in all she has some more strengths and less weaknesses than in previous games, but in the end she still has some glaring weaknesses which will likely hold her back.
Ness looks pretty ok. He seems a bit improved from Brawl but not a lot. His range is still good and stuff like Uair, Nair and Bthrow is still powerful. I don't think he's super good but he's not so bad anymore, I think.
Yoshi is an asshole. I hate him already. He's very good. Eggs are annoying as ****, everything he does is damaging, he kills hella early, he actually has options out of shield now and his mobility is crazy.
Duck Hunt Dog is solid but he looks better than he is. Don't get me wrong, he is very good, but his camping isn't THAT strong. He is also somewhat laggy and punishable and I'm not a big fan of his aerial game. He'll be a strong character though since his zoning is still pretty good and he kills early.
I feel Wii Fit Trainer is a bit underrated. They're pretty decent but I feel like their weird hitboxes need some time to get used to. They're not one of the best characters, but I can't imagine them being really low either. They're decently fast, in their attack speed as well as mobility, and some of their moves have quite some range, although admittedly others are quite lacking. Ftilt and Nair should be spammed at all times and they seem to have a very good dash attack too.