Little Mac, then. The last Punch-Out!! came out not even a full year after Super Sluggers on the Wii.
Xeno also isn't really a new IP. The first one was Xenogears in 1998.
Absolutely nobody thought Shulk was likely but he got in, I don't see why anyone had any reason to think incredibly popular characters that missed one title couldn't happen.
Not to be "that guy" but I was 1000% sure that Shulk would get in. Monolith Soft was Nintendo's new toy at the time, and they even worked in Brawl. Monolith Soft is also a link between Nintendo and Namco, who worked in Smash 4. Namco saw the sale as a way to strengthen their relationship with Ninty. If anything, Shulk was the most obvious choice, and I adamantly said so in my old tumblr blog. Sadly, I deleted my main account and all my other blogs went with it.
He had everything going for him. Relevancy, new IP, moveset potential, underrepresented genre, etc, etc. I don't know if it was bias, but I could've bet my life on Shulk making it in. I spent an unholy amount of time with "Shulk for Smash" stuff. It's the reason I joined this site. Seeing the leak was, in a way, incredibly gratifying. So many dismissed Shulk in favor of the same picks that never make it in, but we saw what happened in the end.
I even predicted (albeit jokingly) his alt costume 10 days before the reveal:
Sorry for this, but it just seems weird people treating Shulk as a surprise newcomer when, in my opinion, he was the most obvious of picks.
And the whole "Xeno" thing is...complicated. It was actually Iwata who came up with the Xenoblade name, the game was going to be "Monado: Beginning of the World" but he thought it would be best to honor the Takahashi's old games. Amazon still has the listing for M:BotW with a bunch of beta images.
That aside, I think Elma AND Rex is likelier than people think, and so is Fiora (either one, I'm not saying there's going to be four XB characters, as much as I'd love that). Did the Hyrule guy that had a "source" on the E3 show floor ever got disproved or anything? If not, then I still think their source confused the Monado with the Aegis sword, or something big related to Xenoblade is happening.