Yoshi is in the theatre with Toad. They watch a movie called Mario & Luigi. After this movie, they see Mario and Luigi bragging on how good they did in that movie, and how awful Yoshi and Toad look onscreen. Yoshi and Toad get angry and decide to prove that they're better then them.
They first go to Peach's Castle, because something weird always happens there. Soon, Peach loses her voice for no appearant reason. Toadsworth sends Yoshi and Toad to collect "Voice Remakabean" from the Beanbean kingdom. Bowser, who happened to be inside, says he will take them in the Koopa Cruiser.
They arrive at the Koopa Cruiser but Bowser's not there. They stand around waiting. 5 hours pass, and Bowser enters to a bunch of sleeping Toads and Yoshis. He roars loudly and everyone boarding boards. They soon arrive in Stardust Fields and are shot down by King Morton Koopa Sr.. Bowser lands in a cannon, random Koopas (including the Koopalings) landed in Boarder Castle and Yoshi and Toad landed in the Unsung Castle.Morton Sr. gets angry because of the intruders and Yoshi and Toad fight him and the rest of the Unsung Enemy Group.Yoshi and Toad defeat them and they give them the Boarder Card, which allows them to pass into the Beanbean Kingdom.
They arrive at Boarder Castle and see the Koopas and Koopalings. They walk past (with the Koopalings hitch-hiking in their mouths/hats) and show the Boarder Bros. their card.
Soon, they arrive at the edge and see Bowser in the cannon, laugh evilly, and walk away. They soon arrive on Hoohoo Mountain, hike down to Beanbean Castle, and ask Queen Bean for the Voice Remakabean. She gives it to them and they go back to the Koopa Cruiser.
They arrive, and Ludwig notes that only Bowser knows how to fix it. They go back to the cannon, but Bowser's gone.
They arrive back at the castle and tell Queen Bean. She says that Bowser was shot to Chucklehuck Woods.
They go there and find Popple. Popple says he found a new Rookie and shows them Bowser. They defeat them and they run to Little Fungitown. Toad and Yoshi go to Teehee Valley.
They go there and get through and see Popple scolding "Rookie" for eating a random mushroomer, and "Rookie" saying that he was hungry. They rip "Rookie's" mask off and he remembers who he is, and eats Popple, who is still scolding him. They go back to Beanbean Castle.
Queen Bean tells them that the Voice Remakabean has run out of power and they must get the Beanstar back from Cackletta to repower it.
They kill Cackletta and Fawful tells them they sold the Beanstar to Popple. Bowser spits Popple (who is still scolding him) out, and orders him to give them the beanstar, but he said he sold it to Queen Bean.
They go back to Queen Bean and she tells them she sold it to Hermie III.
They kill Hermie and steal the Beanstar and run back to the Koopa Cruiser.
Bowser rebuilds it, they fly back to the Mushroom Kingdom...and find out Peach got her voice back. Yoshi and Toad faint.
It zooms out to show Yoshi and Toad watching this in Yoshi Theatre. Mario and Luigi are bragging on how good they were when bragging, and Yoshi and Toad get angry...
Toad: He can jump, Spin Jump, Hammer and Headbutt. His hammer move is Yoshi Ball and his Headbutt move is Yoshi Wallbreaker.
Yoshi: He can jump, High Jump, Hammer and Tongue. His hammer move is Toad Dirt and his Headbutt move is Toad Stick.
Bowser: He can jump, Punch and Fireball. You don't play as him when playing as anyone else, so he has no Partner Moves.