Even though K. Rool is my most wanted newcomer, I've honestly had a hard time coming up with ways to make him unique in Smash. When Sakurai adds a new character, he thinks of what sets them a part from the other characters, and what new stuff they can bring to the table. My main concern was that K. Rool would be too similar the existing heavyweights, like Bowser. However, I think I've found a "theme" for him that another character doesn't already have:
"
Boss Character"
None of the villains currently in Smash really play like they do in their boss fights. K. Rool would mainly use attacks from his boss fights from DKC 1-3 and 64. He could also thrust his belly to attack for a move or two, which no character currently in Smash does. And since his moveset would be mainly based on older games, he would use his old design. He would also be refereed to as a fan-favorite, old school character (Note: his Mii costume in Smash 4 refereed to him as a "retro" character).
Honestly, I think K. Rool is more likely now more than any Smash game before, and that's mainly due to the ballot. We know he did well. The Mii costume is evident of that. To add to this, the Mii Costume was added around the time Bayonetta would've started development, a character who was supposedly chosen from the ballot. If the Mii costume isn't a sign that he did well in the ballot, then tell me this: why did he receive a Mii costume to begin with? Why does the Mii costume not use assets from K. Rool's trophy already in the game? Why does it use his old design that mixes elements with his new design? It makes no sense. I also find it odd how in the interview Sakurai did about Mii costumes, the interview never once brings up K. Rool, yet they bring up Geno. Speaking of which, here's what Sakurai had to say about Geno:
"That’s right. He’s very popular. When talking about older characters, Geno always gets a lot of requests. He didn’t appear as a fighter, but I was able to achieve something kind of close to that as a Mii Costume."
This applies to K. Rool exactly.
Also, the amount of "new" characters to add for each game gets smaller and smaller. There are only 4 new notable characters people will think will get in Smash 5 right now: Captain Toad, Rex, Spring Man, and a new Pokemon rep. And people are even
doubting Rex and Spring Man will get in due to the project plan. So, Sakurai may have to dig a bit deeper for newcomers to add this time around. The Japanese Smash ballot said that it would be used for future titles (Smash 5), so he may have to rely on that a bit. This makes K. Rool's chances very high IMO.
If I were to rate his chances of getting in, I'd give him a 70%. Again, this is mainly due to the ballot and his suspicious Mii costume. I suspect there will be about 8 newcomers and most (if not all) characters from Smash 4 will return. So I'd be surprised and disappointed if he doesn't get in.