Dance Dance Revolution: Mario Mix

Plot

The game opens with Waluigi stealing the four Music Keys, who can grant wishes, from Truffle Towers. However, when he tries to open the door to the room containing the Music Keys, three of them scatter across the Mushroom Kingdom, and the fourth one is kept by Waluigi. From a distance, Toad watches these events unfold and rushes to tell Mario or Luigi, depending on which character the player chose, who then rushes off to retrieve the missing Music Keys.
The keys are recovered by completing tasks for other characters who have found the scattered keys and then defeating them in a dance challenge.  These characters are, in order, Waluigi, Pirate Lakitu, Blooper, Hammer Bros., Wario and Freezie.
Toad and the player's character then return the Music Keys to Truffle Towers. Soon after, Bowser steals the keys, but is followed by Toad and the player's chosen character. They enter Bowser's Castle to recapture the Music Keys, and are promptly challenged by Bowser. After defeating him in a dance-off, Bowser tells Toad and the player's character that he planned to use the Music Keys to fix his tone deafness. This prompts the player's character to use the Music Keys to turn the area around Bowser's Castle into a green field and induces a feeling to dance in everyone, with Toad realizing that this was how the Music Keys were supposed to be used as the game's ending sequence plays.