Yoshi's Island DS (NDS)
Time Trial mode
Beat World 5-8 to unlock the Time Trial mode on the main menu.
Beat World 5-8 to unlock each world's secret stage. In the Secret stages, Yoshi will be a different color...
Get 700 or more points in a world to unlock a bonus challenge panel on the map screen. These bonus challenges are like the ones you get by chance at the end of the stages, but, once unlocked on the map screen, you can play them whenever you wish. Each world has a different bonus challenge to unlock:
Get 800 or more points in a world to unlock an Extra stage on the map screen. Yet another different color of Yoshi does the work in the Extra stages...
Minigames: Hard difficulty
Collect all eight Character Coins in a world to unlock a hard version of one of the minigames. The hard minigame that is unlocked depends on the world:
Unlike the other unlockables, the game won't tell you that you've unlocked these, but they do appear in the Minigames mode available from the main menu.