“Users will be required to download this update prior to using the software’s online multiplayer features,” says Nintendo on its support page. “Because of this, we strongly recommend that all Super Smash Bros. players download and install this update data.”
This update will also improve gameplay and unlock the game’s online mode.
In order to install the update, users can either go to Nintendo’s eShop or go to the 3DS’s setting menu then select “perform system update.”
Super Smash Bros. Wii U is slated to launch this holiday season.