I could see Sonic making an appearance. That'd be rather fun, I think.

I'm really excited to see Metaknight. I was saying that he needed to be in there since last time.

Maybe get a few more of the Starfox characters in there, DEFINITELY want to see more Earthbound characters in there.

Mike from Star Tropics would be fun. Boy and girl version

I'd also love to see Erdrick from the original Dragon Warrior series. That'd be damn cool, and it looks like Nintendo is collaborating with other companies this time around so it may just happen.