Isaac - Golden Sun (Why cut him? Though I think it's because he'll end up playable)
Vaike - Fire Emblem Awakening (Severe lack of axe users in Smash, AT is as good a place as any to get the ball rolling)
Prince - Katamari Damacy (I know this hasn't appeared on a Nintendo console [stupidly, it's a perfect fit], but Namco made this so it should be there)
16 Bit Brown Yoshi - Yoshi's Island (This is a weird one... But I've got this fixation on the idea that there should be an assist trophy accounting for Yoshi's transformations in Yoshi's Island. Brown Yoshi isn't playable in Smash, so it'd work. It'd have three different attacks. Turning into the mole, which would dig under the stage and then pop up in random places for an upward launch. Turning into a copter, where it flies around and drops low-damaging eggs on the battlefield. Turning into the car, where it does a quick dash, like a low powered Bullet Bill)
K. Rool - Donkey Kong Country (I'd rather he be playable. but he loses compared to Dixie too, so if there's some sort of DLC, I'm betting it'd only be one of them and he can be an AT, he fits that role better than she does. Throwing his crown boomerang style, doing short hops and raining down cannonballs. It writes itself.)
Inkling - Splatoon (As much as I think it'd be a good idea for Nintendo to have them be playable, I think there'd be a lot of outcry about this. I mean, people are irritated over Greninja because they think he's unworthy, and Greninja is from a popular, tried and true series. So it might be good to first introduce Inkling as an AT, Sprays down paint that speeds up the person who used the AT when running across it and slowing down opponents on that patch of paint. It works well)
Reyn - Xenoblade Chronicles (This is so strange to me. Reyn should have been part of Shulk's FS. Riki shouldn't have been both in it and as an AT. Feels unnecessary especially since Reyn is a much larger and important character than Riki is in the game.