Bad news is that the 3DS version might limit the number of characters in the game.
"The reality of the situation unfortunately is that there are certain limitations on the 3DS," Sakurai said. The 3DS and Wii U versions of the next Smash Bros will have the same library of characters.
"So we're forced into the situation where we may need to reduce some characters to a certain degree. but we're really working hard in order to include as many characters as possible."
http://kotaku.com/dont-expect-a-lot-of-third-party-characters-in-the-nex-513203533