With Nintendo releasing the SNES app last week for the Switch, many people will definitely be playing the SNES classic "Super Mario World 2: Yoshi's Island." For those who didn't already know, there is a secret 2-player mode that can be enabled. Here's how to do it:
On the level select screen, press X X Y B A. If done correctly, a song will play and the level select screen will change. There are a bunch of minigames playable that you would have to otherwise find in minigame huts throughout the game, and there are 2-player variants of some of these games!