Wuhu Island

Wuhu Island, originally known as the Wii Fit Island, is a location which first appeared in Wii Fit, and has since been featured in several Nintendo games. Most of the games it appears in are Mii-focused, but all at least have Miis playable. Its most notable appearance is as the setting of Wii Sports Resort.

Mario Kart series
In Mario Kart 7, Wuhu Island appears as the setting of the Wuhu Loop and Maka Wuhu courses, and the Wuhu Town battle stage.

The Wuhu Town stage reappears in Mario Kart 8 Deluxe, where the island has been redesigned in a way that fits the game's depiction of the Mario universe. Whereas Mario Kart 7 featured a generic Battle Mode theme for all of its stages, Wuhu Town now has an arrangement of the Wii Sports Resort main theme, as the two race courses previously did.

Super Smash Bros. series
Two stages featuring Wuhu Island were introduced in Super Smash Bros. for Wii U, both returning in Super Smash Bros. Ultimate.

Trivia

 * In the running activities of the Wii Fit series, 15 sprites from Super Mario Bros. are hidden on surfaces around the island.