Nintendo as just released Super Smash Bros. Direct revealing details about the 3DS and Wii U versions of the game.  The 3DS version is aiming to be released this Summer before the Wii U version in the Winter of 2014.  

      The 3DS will have fighters at 60fps with summons running at 30fps.  The fighters will remain the same on both systems.  The Stages will be different between 3DS and Wii U with some stages that appear on both including console specific tweaks.  

Oh one more thing, some new fighters will join the fray.

Source: Nintendo