Yoshi's Island

Yoshi's Island is a large, tropical and mountainous island inhabited by the Yoshis. It first debuted in Super Mario World in 1991, in the same game Yoshi entered the gaming series.

Super Mario World
During the evens of Super Mario World, Bowser and his children attacked Yoshi's island, forcing Mario to team up with the natives to stop the Koopa army. Bowser gave control of this island to Iggy Koopa who kidnapped a red Yoshi egg and hid away in his castle. For a full list of the levels, see Yoshi's Island Levels.

Super Mario World 2: Yoshi's Island
In Super Mario World 2: Yoshi's Island, Yoshi guided Mario through Yoshi's Island as a baby. In this game, Yoshi's Island was shown to have geography and climates similar to that of the mainland Mushroom Kingdom.

In Super Smash Bros.
Yoshi's Island appeared as a stage in Super Smash Bros., Melee, and Brawl, though each iteration's stage is completely different from the first.

Super Smash Bros.
The original version of the stage mirrors the Yoshi's Island from the Nintendo 64 game, Yoshi's Story.

Super Smash Bros. Melee
The Melee version of the stage mirrors the Yoshi's Island from Super Mario World. Lining one side of the stage is a sideways Warp Pipe, with a hill on the other side. Special blocks are found here. The player can jump on them, but if they are hit, the player falls through them until they stop spinning.

Super Smash Bros. Brawl
The Brawl version of the stage mirrors the Yoshi's Islands found in the Yoshi platforming games such as Super Mario World 2: Yoshi's Island and Yoshi's Island DS. Simplistic in design, Yoshi's Island contains no real hazards and, like its predecessors, features Shy Guys.

Trivia

 * In a level in Super Mario Sunshine. A Pianta says to Mario "This island used to be inhabited by Yoshi's" referencing the fact that Delfino Plaza could very well be Yoshi's Island after the Pianta's took over.