Super Punch-Out!!'s Secret Two-Player Mode Has Been Found After 28 Years - Kotaku

Super Punch-Out!!, the 1994 SNES game released as a sequel to the 1987 NES original, is like its predecessor a single-player game.

This isn’t unlocking a single level, or buffing your stats, this is basically adding an entire new game mode, while also doubling the player count and bringing the boxing game into the multiplayer arena after spending 28 years as a single-player experience

(Note though that this isn’t the first time we’ve been able to play a Punch-Out!! game in multiplayer, as the Wii game had a two-player mode, though it was only against a Little Mac clone, not the game’s roster of weird and wonderful AI characters.)