Princess Peach is the princess of the Mushroom Kingdom, and the former girlfriend of Mario. She was first mentioned by Mario in "Sonic For Hire: Toad" when he told Sonic that Toad was suppose to be keeping an eye on her, but kept slipping up, and later mentioned again by Mario in the "The Battle Part 2", who was dying from the spike pit. He told Sonic that, "If you see the princess, tell her I said....she's a bitch." Tails mentioned her in "Sonic for Hire: Link". Sonic and the group had no idea what they were doing since they were new at the whole crime family thing, so Tails sugested that they find her since she was close to Mario, hoping she'd give them some pointers. Link then showed up and was willing to lead them to her but ends up leading them to a place called "Margarita Manor". Her first major apperance was in "Sonic for Hire: Peach". It was shown she was still locked up in Bowser's castle when Sonic and Tails found her. Sonic then revieled to her about Bowser and Mario's deaths, including Mario telling Sonic to tell Peach that she's a bitch. Peach then started asking Sonic and Tails if they were her new captors and such, reveiling she had stockhome syndrom and would fall in love with her captors. She failed to give Sonic and Tails the pointers they needed, but fortunately Earthworm Jim, and Dr. Eggman entered the scene with Princess Potato (a princess from a Mario rip off game called "Super Itailian Laborer Town") who knew Mario better and was going to give Sonic and the gang pointers. With that, Sonic and co. left the castle only for Sonic to tell Peach to call him when she's not crazy. She was last seen with Link who decided to give her a makeover.
Peach made her next appearance in "Wrestlemainia", where Link brought her to Sonic's office to show off her new look. She saw the girl grunt (from Double Dragon), Mother Brain, and Amy fighting over Sonic, and she joined in too. Sonic had enough of it and had all four ladies fight. Peach started fighting Mother Brain, only for her to knock her of and push her onto Amy (killing the girl grunt in the process) and Peach started strangling Amy, but Amy kicked her off and knocked her into Mother Brain.
Peach's next apperence was in "Sonic for Hire: The Red Carpet", where she was sitting in the movie theather.