Yokai Watch is probably the biggest third party Nintendo exclusive (ok I think there are some mobile spinoffs) franchise in years. It's a pop culture phenomenon in Japan and the 3DS games have sold millions of copies and are undoubtedly system sellers for some. Its cast certainly has more relevancy and notoriety than a lot of Nintendo characters we haven't seen in years. Jibanyan as a DLC fighter would be a pretty big acquisition. Not to mention Yokai Watch is coming to the states, and while there will be English names, Jibanyan will be untouched.
I would like to see Eggman as well. He's gotta stay in a robot though, I don't want to see his lanky ass running across the stage. They could be lazy and make him a heavy Bowser Jr. clone, or maybe his gimmick could be that his robot can transform which changes the specials. Think of it like being able to switch between custom moves in battle.
Also here's a curveball: MARIO MAKER
That's a pretty distinctive outfit Mario's got there. Way better than a damn lab coat. Maybe he could summon up random enemies and items from the Mario games. Also a Mario Maker stage with a bunch of crazy elements is pretty much a lock for DLC or Smash 5.
And let's go even nuttier... 8 BIT MARIO
I'm not sure what moves he could have... but since Nintendo is running out of huge characters to put in Smash, I can see them having a lot of Mario variations. Mario, Dr. Mario, Mario Maker, Paper Mario, 8-Bit Mario etc. They can be the shotos of Smash. EVERYONE LOVES SHOTOS.