I think I'd like a shot at that
[collapse= Rhythm Heaven Character]
Rhythm Heaven Character
1. How many diverse options does this character have?
Many people bring up the possibility of a rhythm-based moveset, where hitting to the beat of the music powers up your attack. However, I'm pretty sure this is both technologically and conceptually impossible, especially since a song doesn't usually have a singe defined beat. The alternative is a timing-based moveset where you're required to string your attacks in the right amount of time. Too late or too early and you won't do as much damage and your combos will falter. This is similar to Marth's Dancing Blade from Melee. This timing gimmick could be applied to all of the specials, and perhaps also the smash attacks. What they attack with is another thing that separate them from others, as most ideas include them using objects or people from all the different minigames in the series as weapons.
Wrestler is the exception, in which his identity is using actual wrestling moves as a grappling character.
2. Are their moves or abilities diverse from the rest of the Smash cast?
Partially. A timing based moveset is something that's not yet been done, but moves that require good timing are spread all throughout the series as things like Link's Fsmash, and most notably, Marth's side special. In fact, the idea of this whole thing originated from Marth. Also, the use of various objects as attacks is treeded water with both G&W and Villager doing just that.
Wrestling is something characters have touched upon, but never fully realized. Bowser's done it in his side-special and down-throw, while Captain Falcon/Ganondorf both have moves that consist of latching onto opponents.
3. Has the concept of the character been done before?
In terms of full movesets: no.
4. Are the character's abilities and moves provide enough to be entertaining?
Timing based movesets being fun is something debatable. A first-time player probably wouldn't have a fun time playing using moves he has no idea how to pull off. However, Olimar has the same effect on newer players so it's not something that the series hasn't seen.
Wrestling as a moveset would be something stylish, relatable, and entertaining to watch. I could see Wrestler being a popular character if he is added.
5. How visually different is the character in terms of body shape and looks?
I'll divide this up.
Rhythm Girl and Karate Joe both suffer from the fact that WFT share some attributes with them. Rhythm Girl is another nameless girl who often appears with white skin, and Karate Joe is either fully monochromatic or blue, depending on how he's depicted. However, I believe they can be rendered to look unique enough.
Marshall is a much more simple design and only risks looking similar to Kirby, which is a large stretch. He'd probably be the most identifiable Rhythm Heaven character too.
Wrestler is very similar to Captain Falcon in body structure, but his wider shoulders and generally more cartoony look set him apart enough.
6. Does it fit the character well enough?
For Rhythm Girl and Marshall, the fact that they don't do much of anything in the games they appear in allows them to pull off more farfetched things. I think it fits them very well, Marshall especially.
Karate Joe has more of a problem, considering he has a set series of actions he does in game. It would look a little jarring to see someone you'd assume to have a karate-style moveset and end up with him fighting using a badminton and trampoline.
And while Wrestler doesn't actually do any wrestling in the game he's from, it's pretty easy to excuse him considering his appearance.
Overall Rating: 7/10 (Rhythm Girl, Karate Joe, Marshall), 6/10 (Wrestler)[/collapse]
I collapsed this because I didn't realize we were talking about Little Mac specifically at the moment.