Instructions
Return to the Puni's tree after defeating the boss at the end of Chapter Two.
Speak to Petuni, Punio's younger sister. She is the Puni with the pink antenna.
Agree to play "Stump Petuni" when she asks. Mario will then have to ask her a question and she will have to guess the answer. There is only one question Petuni can answer correctly.
Ask "Who does Mario like the most?" Petuni will reply "Princess Peach," and will give Mario a Mystic Egg for letting her win the game.