So far these are the newcomers for Super Smash Bros. for Nintendo 3DS/Wii U. These pictures are their reveal shots from their respective trailers. This will be updated when a newcomer is revealed.
2/13: Added Little Mac
4/8: Added Greninja
6/10: Added Palutena and Pac-Man
6/15: Finally added Mii Fighter
7/23: Finally added Lucina and Robin
8:29: Added Shulk