The Flutter Challenge.
Flutter Challenge is an unlockable minigame in Yoshi's Island DS. The player controls one of the Yoshis and attempts to Flutter Jump as far as they can to earn extra lives. A Hard Mode can be unlocked by collecting all eight Character Coins in World 2.
Easy Mode
Players flutter to the left and are very high up, making it easier to recover if the player misses a flutter. The controls are pretty tough here, making it easy to miss a flutter...
Hard Mode
In this mode, players fly to the right instead, where the ground is a bit higher up, leaving less room for mistakes. However, the distance between each marker is much shorter, cancelling out the ground distance. The controls are smoother here, making it easier to fly seemingly straight across without missing a flutter.