Right now, you can submit which fighter you would like to see appear in Smash Bros for 3Ds or wii u as a playable!!
you can submit your characters here: https://cp.nintendo.co.jp/us/
Here is my list:
- Banjo & Kazooie
- Shovel Knight
- Wonder Boy
- Vector Man
- Earthwork Jim
I'm sure there's others I can't think of at the moment. Also, there will be some DLC coming soon - new mii fighter costumes, Mewtwo, Lucas...lots is coming!