Today, Smash Bros series creator Masahiro Sakurai announced that the Wii U and 3DS version of the game will release separately. The reasoning behind the release delay is because of the debugging process for both platforms. Here he explains the situation:
“Checking is done both domestically and overseas, so for a game like Smash Bros., several hundred people are employed.” Sakurai said. “So, debugging alone becomes a huge project. So much so that one of the biggest reasons for the separate release dates for the 3DS and Wii U versions was so that we could shift the debugging periods.”