Star Coin 1: Mario must stay on the leftmost Peepa platform at the start. It will take him to the Star Coin, where he must jump with correct timing to get it.
Star Coin 2: Shortly after the first Star Coin, the Peepa platform passes below a platform with a + Clock below it. Hitting this block reveals a vine. Using the Peepa platforms in this new area by wall jumping when they turn vertically, the Star Coin can be reached.
Star Coin 3: After the Gold Ring and Big Boo, Mario must stay on the middlemost Peepa platform. It will eventually take him straight through the final Star Coin just before hitting the Goal Pole.