Can't believe some of the things people are saying in this thread. Actually, I guess I can.
Few things:
1. The Koopalings are more iconic than Bowser Jr. This is so retardedly obvious I have to wonder why people are even questioning it (aside from assuming some of you are kids). Keep in mind that no one's advocating them to be playable since everyone's aware of how much of a technical nightmare they'd be.
2. Bowser Jr. has a significant amount of hate from Mario fans. This also falls into the "retardedly obvious" category. Not to say he doesn't have fans, he does, but there's a LOT of hate. Daisy and Waluigi fit that bill too. And yes, that's a big problem for him.
3. These hierarchy lists are pretty bad, especially those of you caring about the storyline aspects so much (and giving individual rankings for these characters? come on guys, you're better than this). The only thing that matters is that Mario, Luigi, Peach, Yoshi, and Bowser are important, everyone else pales in comparison.
4. I like lists.
Regardless over who, point is that It's not really misrepresentation of the series with or without them (Toad and Jr) - I don't really know what to call it, so I'll let toise come up with it. (If he's not mariosick)
Over-representation.
@Shino: If you don't like motion controls then yeah, you're kinda screwed (since those aren't going away, though two of the games you listed can be played with a GC controller). Not sure how you feel about difficulty, but I'll mention that all three games you mentioned were par for the course in their respective series.
@Scooby: There should be a decent amount of sword stuff with Goroh too. I always imagined him spinning his sword around the way you'd swing a ball and chain (as opposed to the twirls Pit does).
And lots of flailing too.
Also hoping you have something a little reminiscient of the tackling/spinning attacks from the games, but I can live without those as long as the whole thing shows off how boisterous he is.
@Koops: Car Slam? Come on, at least get the name right.
edit for Koops: Baby Daisy's in two games and Kamek's in NSMBWii.