Mysterious Mine Carts owner
From the Super Mario Wiki
The Mysterious Mine Carts owner is a friendly old Hoohooligan man who lives underground and runs the Mysterious Mine Carts ride in the Beanbean Kingdom. He appears in Mario & Luigi: Superstar Saga, where Mario and Luigi can talk to him in order to play the minigame. He is usually seen sitting in his rocking chair alongside his beanish dog. During the mine cart tutorial, he rides on a rocking chair with wheels that is pulled along the tracks by his dog.