Peach is...sigh.
Half of me wants to go on about how much potential Peach still has, how much room she has to grow, how well she can do against Dedede, Falco, Snake, Marth, and other top tiers which seemed to flat out beat her early in the metagame.
How her ATs like Bonewalking, free turnip pulling without B-stick (Dark.Pch's analog stick tilt method), etc will make her continue to rise, how we continue to find more, better applications of the fantastic tools she has available.
But...I'm not so sure if it is true anymore. Peach's largest flaw of them all is, of course, her ability to kill. Past that, though- her bad airdodge. She has enough return to ground options (especially when you utilize footstooling) to make it back down normally. She absolutely does not have the tools to get to the ground against MK. Her airdodge is the worst in the game by an utterly enormous margin, with a full half-second of lag, to the point where airdodging has to be avoided by all means as a return-to-ground option. Combine that with the fact that she's one of the slowest fallers in the game, and she is juggle-bait for Metaknight.
Peach has excellent spacing tools, moves that give her frame advantage on shield, other moves that let her frame trap (some characters can't punish a SH dair on shield crossed up to land behind them before she can nair, other characters can't punish fair > jab). She just gets wrecked by Metaknight playing the proper playstyle. Luckily...most MK's don't play it right.
I'd like to see Peaches use dtilt more; her dtilt imparts enough shieldstun that most of the cast can't punish it OOS, and has disjointed range similar to MK's ftilt. 0.0 It unfortunately has a slow startup time (which is why most people don't use it), but the startup animation actually makes your hurtbox smaller. I have had a dtilt cause MK's ftilt to miss due to the hurtbox shrinkage, and then connect with him between the hits of his ftilt.
I also think Peaches need to footstool opponent's shield's as a recovery reset method more, as opposed to airdodging (which never goes unpunished).
Peach has, however, a lot of flaws that I don't wish to particularly advertise here. I'm not sure where to really argue her in the tier list. =/ She probably still has the most
potential growth of any character in the roster, however.
I will note, however, that all of this evaporates in Doubles. Peach is the Inui of the Brawl roster. Her largest issue in doubles is double Metaknight; she needs a teammate that doesn't get juggled by him (Larry and I had this issue with Peach+Falco, and Superboom and I had this problem with Peach+Snake).
Peach+Metaknight works fantastically. So does Peach+Snake (except against double MK), Peach+Wario (I love that one), and a number of other team combinations. I suspect Peach+G&W might work well too...but I haven't tried it lately. All of Peach's grounded moves send opponents up as well, setting up for juggles (which is why Peach+MK and Peach+Wario works so well).
I think Peach+Snake, with a Snake that seconds MK for the double-MK team, is probably the best setup, but I'd like to try teaming with a high-level Wario sometime because the few experiences I had with that team were fantastic.
A couple other notes:
* Peach's dash attack is FANTASTIC. The invisible disjoint is so great that she can dash attack Green Greens blocks with proper spacing and detonate them without being damaged. She can also space it perfectly on Marth's shield so that he cannot up-B OOS.
* Peach's nair is three frames, her jab is two. She's fast. Groundfloated nair is the best way to punish a lot of stuff.
* Peach can catch items during her aerial by dropping float, an interesting side-effect of the removal of Melee float-canceling. IMO, this is an enormous advantage against Diddy that no Peach really utilizes.
Mikey Lenetia brought up what I consider to be the biggest issue with Peach;
STAMINA. Peach is a mentally exhausting character. Almost everything requires a lot more focus; even punishing random rolls sufficiently takes a lot more precision than with other characters (fsmash is slow and reaches higher in the air than the ground, jab and dsmash don't do that much damage since a roller will usually only take one or two hits of the dsmash), and usually requires that you do something like a groundfloated autocancelled aerial (nair or bair) very quickly.
Though, keep in mind that my regular practice partner plays Lucario. xD
Under pressure? Tired? Peach performs far worse. Peach gets punished very badly for lack of precision due to her bad airdodge, and similarly requires you play a lot more precise to get your punishments. Her aerials only grant you frame advantage when spaced perfectly. Her turnip game is not for damage as people think, but positioning advantage and option reduction, and becomes very hard to take advantage of when you're not playing at your best.
I'm famously inconsistent in Washington; in fact, in my tournament history, it's extremely common for me to beat players in winner's bracket and lose to the same player in loser's finals, because my stamina saps. Similarly, at Apex- I beat Vinnie in a MM, two stocking him and beating him on his counterpick, but lost 3-0 on the livestream later in front of the crowd. Players in Western Washington took it upon themselves to go out of their way to trash talk me when playing notable matches against crewmates because it works. >_<
In fact, almost all of the top Peaches are very inconsistent in this manner, beating good players and then losing to bad ones. She's, I suppose, an emotional character, subject far too much to the moods of her player.
The only Peach player to demonstrate any kind of consistency was Edrees, when he played.
Oh, and Peach's best pullable item is Mr. Saturn.