Which Smash release first added a mode for up to eight players fighting at once?

Super Smash Bros. for Wii U was the first Smash release to add a mode for up to eight players fighting at once.

The feature is called 8-Player Smash, and it debuted in the Wii U version released in 2014. It supports local multiplayer using combinations of Wii U GamePads, Wii Remotes, Wii U Pro Controllers, and GameCube controllers with Nintendo’s adapter.

Eight-player battles are restricted to selected large stages because the arenas must accommodate many fighters and effects simultaneously. The mode is also local-only rather than an online feature. Super Smash Bros. Ultimate later retained eight-player battles, which can make it seem like that game introduced them.

The distinction matters because the Nintendo 3DS and Wii U versions are closely related but not identical. The 3DS edition does not include 8-Player Smash; it is specifically a Wii U feature. The game’s 2014 launch therefore marked a major expansion of Smash’s party-multiplayer format beyond the four-player battles associated with earlier entries.