You have earned my wrath. Prepare to be attacked by an unnecessarily long comment that I wrote for a different thread (
http://smashboards.com/showthread.php?p=4943902#post4943902 comment number 3039) that I definitely do not want to type again. This shall prove that she can most certainly fight, despite that she never gets the chance due to the plot.
"I know a good deal about the Princess, so I'll take this. In Super Princess Peach, she had a set of powers derived from the vibrational energy of Vibe Island. She could wrap herself in enemy-damaging flames, use water to move at super-speed (Sorry Sonic. You aren't alone.) through the process of hydroplaning, self-heal through concentration; and lastly, her most "broken" ability: infinite flight by enveloping herself in a small tornado.
Then, there are her super-powerful abilities courtesy of Perry (which I consider against the "rules" to this thread, and thusly, are banned). But because these (the vibrational) powers were implied to be situational due to the location, I suppose they are disqualified here.
Now on to her floating powers. She is somehow light enough to defy gravity by using her dress or parasol to catch air and float (which, technically, could last forever until she either decides to come down or runs out of air. But they have to put a time limit on it, or else it would be SO broken.).
Now to the Paper Mario series. In the original Paper Mario, she was only playable during brief End of Chapter levels. In one of these, she obtained an item called a Sneaky Parasol, which could transform the holder in to anyone, provided they were within range of the purple-colored smoke it emitted. She was also shown, during a mini-boss fight with Kammy Koopa (during the final boss fight), to be able to increase someone else's powers by focusing on them, demonstrated by increasing the attack and defense power of the Star Kid, Twink, every turn. Kammy assumes that this is because Star Kids (and Star Spirits) gain their powers from wishes; however, this cannot be true for several reasons also shown in-game: 1) To get a wish granted, a Star Kid must deliver the wish to the Star Spirits in Star Haven, who will then either approve of it, or reject it depending on the intentions. This could not happen because the Star Spirits were helping Mario fight against a Star Rod-fueled Bowser, who would otherwise be invincible. 2) If the Star Spirits approve the wish, they then use the Star Rod's wish-granting powers to make it come true. However, before the beginning of the game (in the opening cutscene before the Title Screen) Bowser stole the Star Rod and was using it to grant all of his wishes only. Thusly, any wish Peach would have made would be null and void. This method of powering up others also explains some things I'll get into later.
Anyways, also in Paper Mario, she again focuses and upgrades the Star Beam (the ultimate move used by all seven Star Spirits together to reject the Star Rod's power, should anything ever go wrong) into the Peach Beam, making it powerful enough to be successful this time (The Star Beam had been weakened by a cursed arena Kammy Koopa built to give Bowser the upper hand.).
Also, in Paper Mario: The Thousand-Year Door (as well as Mario & Luigi: Superstar Saga) she is shown to be pure-hearted enough to undo several curses that were at least a millennium old.
In Super Paper Mario, she is shown to be able to use her trademark parasol as an unbreakable shield (the exact extent to which is unclear, but in-game it can reject flames, blade-edges, a swarm of stampeding Muths [the counterpart to a Wooly Mammoth], extreme temperatures, freezing breath, status-inducing gas clouds, an avalanche of stone, magic, lasers, missiles, curses, lightning, et cetera.), and she comes equipped with her standard long-distance floating abilities. Now for her main fighting powers...
What most people don't know about the Princess is that she was one of the main party members of Super Mario RPG: Legend of the Seven Stars, and she was one of the most important party members in the game for her special abilities. She was an expert at healing, with three special moves for that effect. One did near-perfect healing on one member, one did great healing for all party members, and another brought a party member back from running out of health. But she also had three other special powers. She could put either one or all enemies to sleep, and her most powerful attack, Psych Bomb, involved her concentrating, and then everything on the enemy's field would be engulfed in an explosion for amazing damage.
And her last power is her most useful power: Mute. Mute is a move that revokes an enemy's usage of special abilities. That is why I think Peach is up for higher tier than everyone thinks. Lucas or Ness without PSI powers makes for two normal children. Sonic without speed leaves a regular hedgehog (except for the whole "I'm blue and I can talk!" thing). The list could be longer, but the move still needs to be debated for some basic ground rules as to what it can work on. Anyways...
The last thing I have to say about Peach is that she has one other vague power. No, it isn't her affinity for giving everything a heart or flower theme (mainly [or only] in the sports spin-offs, as well as the Mario Party games), it is her odd ability with Item Power-Ups. I cannot remember what game, but in one of the final boss battles with Bowser, when he is flying around in the Koopa Clown Car with Peach in tow, she throws Mario a Mushroom on occasion, despite having no logical place to get them from. This also happened in the semi-final boss battle against Elder Princess Shroob in Mario & Luigi: Partners in Time, where on a small floating platform hiding behind a throne, she is able to throw the heroes a healing Mushroom every few turns, also with no logical place to get them from. In Super Mario Galaxy, she sends Mario (or Luigi) five 1-UP Mushrooms every now and then, still with no logical place to get them from (or, for that matter, no logical place to send them in the mail to Mario). So, how then?
It is possible that she is then creating the items instead of the low chance of finding them, as it has been shown that Toadsworth and some others can create ? Blocks with items inside (Toadsworth uses his cane) by some method, possibly magic. It is possible then, that the Princess could also be using this magic to make the items she sends/gives to Mario, and could also then make an infinite supply of 1-UP Mushrooms for herself, and theoretically, never (permanently) die. However, it seems that this Mushroom-making process takes some time, as it takes a couple of minutes to make them.
Anyways, that is all I can think for the Princess. So, any thoughts?"
Now you should see that she is incredibly powerful, but the creators of Smash chose not to let her be. If characters were capable of the powers that they actually have, the princess would be much more powerful. Any response?