Next month’s issue of the Japanese magazine should be quite smashing.
http://www.nintendoworldreport.com/news/38087/corocoro-promises-full-list-of-smash-bros-3ds-characters-stages
Monthly Japanese publication CoroCoro says they’re featuring a list of all characters and stages for the upcoming 3DS version of Super Smash Bros. in next month’s issue, according to an ad on their website.
The issue in question is slated to come out on August 12, roughly a month prior to the game’s Japanese release date of September 13. The 3DS and Wii U versions of the game are said to feature the same character roster, so this reveal should apply to fans anticipating either. However, the list of stages is unique to each version, so some secrets will remain even if CoroCoro follows up on its promise.
There is some concern that the publication’s presentation won't be as revelatory as is implied, since many remember a similar promise made by CoroCoro prior to the release of Super Smash Bros. Brawl for the Wii. In that instance, it turned out that the character list they promoted showcased only characters that had already been unveiled via the daily updates from the Smash Bros. Dojo.