For the first time in the series, Super Smash Bros. is on a handheld system, the 3DS. Unfortunetly, there is a slight issue. If players want to battle on the game's online multiplayer mode, they will have to download and install the update from the eShop.
While you can still play any of the game's offline modes without the update, Nintendo "strongly recommends" that all players download and install the update.
Along with enabling online multiplayer, this update also adds various gameplay balance adjustments designed to create a "more pleasant gaming experience," Nintendo posted.
For those who already have several hours logged, don't worry. Nintendo said that all your previous save data will remain intact after the update is complete.