The pre-order page for the game reveals that Peach (and Bowser) will be allies who aid the brothers. It is unclear whether Peach will be a party member or a helpful character they encounter, but the trailer suggests she is not in danger. According to the section about Peach, she may play a more active role than in previous games and could potentially become a party member.
The reveal trailer also hints at Peach’s more active involvement as she is seen riding alongside new characters, appearing to enjoy herself and not in distress. While there is a possibility that Peach may be kidnapped and eventually rescued to become a helpful ally, her safety does not seem to be the main focus of the adventure. The primary motivator of the adventure is yet to be revealed, but it is reassuring to see Peach holding her own.
