Super Mario Sushine sees the Nintendo hero on a mission to save Delfina Island from the chaos generated by the impostor Mario Shadow. The protagonist will be able to freely explore the island also thanks to his historical dino-mount, Yoshi.
To unlock Yoshi you first need to save its egg from the clutches of Shadow Mario in the Piazza di Delfinia, after completing the 4th episode of Girasolandia, the amusement park. To beat Mario Shadow just chase him and hit him repeatedly with jets of water: when he has little life he will begin to blinking red. Once collected, the egg will ask you to be restocked with any fruit; you can easily find the fruits on the trees scattered around the island.
When you have brought fruit to the first egg, others will appear in the various levels of the game, while requiring a type of specific fruit. If you bring them to him, the eggs will hatch and you can ride Yoshi to explore the stages faster or solve some puzzles. To ride the little dinosaur, just jump on it. You can also float in the air along with holding him the A key, while to attack with a shock wave on the ground you have to press L in mid-air.