False Peach

"La La La Lala, Sweet."

- False Peach, taunting Solid Snake after defeating him

False Peach, or Peach's Shadow, by the fans, is the corrupted form of Princess Peach, created by Subspace. She runs as a Commander of the Subspace Army, along with False Zelda, Ganondorf, Bowser, and the controlled Master Hand, under Tabuu's Order.

Background
During the Battle of The Midair Stadium, Princess Zelda was rendered weak after she was freed from the clutches of the Petey Piranha. Having Kirby saved Princess Peach, Zelda was defenseless, so Wario took a shot at her with the Dark Cannon, turning her into a trophy.

Having time past, Kirby and Peach were left alone in a grassy area, but Kirby ran away, thinking he saw or heard something, Peach then tried to stop him, but then a loud noise struck behind her. Peach was very surprised as she saw Bowser charging up a Dark Cannon towards her, Peach gasped and hesitated for too long that she was turned into a Trophy. Moments later, False Bowser was seen alongside the real Bowser. False Bowser then deteriorated into Subspace Bugs. While deteriorating, the Subspace Bugs engulfed Peach, creating False Peach.

Soon after that, False Peach was seen up at a high peak of a mountain, attempting to permanently Freeze Mario and Pit with the Dark Cannon. She was caught doing this by Link and Yoshi, and was then defeated, but not for long.

Bowser had soon returned and had captured Peach and brought her to the Halberd. There, Peach and Zelda were seen caged and hanging on the ceiling. Subspace bugs, again were attempting to reincarnate False Peach, and also created False Zelda. They see 3 beings, and look at them with incite hatrid. These beings were Meta Knight, Lucario and Solid Snake. All 3 were forced to battle against the False Princesses, and then defeating them soon after. Upon their defeat, the False Princesses were shrouded in dust, only to see the true forms of Peach and Zelda.

After that, False Peach's "Essence" (her remains in Tabuu's Great Maze) is then seen the Great Maze. After she is defeated, she is not heard of again in the main storyline.

Appearance and Style
False Peach shows a strong resemblance to her own Pure Form, Princess Peach. The only differences in her appearance is that her eyes glow a bright yellow, her body is shrouded by a purple aura, and she is rendered to be darker.

Her fighting style remains the same as her original, she can still use her umbrella, heart power, levitation and other powers. False Peach has added some other attributes though, as she is capable to transform into Subspace Bugs. She can also carry large and heavy things that she simply cannot carry in her pure form, such as the Dark Cannon. Like most reincarnations, she can manipulate Peach's body to do what she likes, also to control Peach's mind, making Peach have no complete idea what she is doing.

Trivia

 * False Peach is not encountered in Boss Battles, even though she is a boss.