It's official. Nintendo will be releasing an update for Super Smash Bros. on Wii U and 3DS July 31st. Announced officially on the Super Smash Bros. Facebook page, the update will add Tourney mode and the option to post Replays on YouTube to the Wii U version. There will also be paid DLC of new Mii Fighter costumes and new stages for both version, though we'll have to wait for more details.
From what we know, two types of tournaments are going to be implemented. There's going to be Community Tourneys, in which a player has a limited amount of time to accumulate the most points, and there will be Regular Tourneys, which have their own set of rules and can only happen at designated times.
To use the YouTube replay feature you're going to need a Google account. There has been no word on an increase of price in new Mii battle costumes; however, you'll be pleased to know that the a tourney update is free if you already own the game.