Robin/Avatar
Popularity: Seems to be well below that of Marth, Ike, Roy, Chrom, Lyn and Lucina. She doesn't even seem more popular than Tharja. At least in Shortie's poll. Japanese fans, as discussed before, want Roy and see Chrom as the most likely new rep.
Relevancy: She's the player character for the latest FE game. This does make her less defined as a character than the others though.
Design: She can be pretty much any class, which means she doesn't have to use a sword, and she can use magic and so forth. There's a lot more freedom with her move set. They could even just choose to give her moves on the basis of making her more different from the other SSB4 characters. This gives her some more interesting possibilities. But as such, a lot of her moves overlap with other FE characters. That, and the lack of specificity also makes it harder to say what a "fitting" move set would be. Final Smash seems a bit easier though (have a bunch of generic FE units attack!).
Roster and Competition: Fire Emblem, in my view, is unlikely to get more than 3 slots. And if there's 4 slots, I pretty much expect it to be Roy + someone else. And there's a LOT of strong competition for that slot. Roy and Chrom seem to be the most wanted and the most expected. But Lyn and Lucina are also fairly popular - more popular than Robin. And they both are important characters as well.
Robin chances: 4%
I don't remember exactly what I gave the others, but I'm pretty sure I gave enough that there's very little left for Robin. If Robin gets in, we'll know that unique move set potential is much more of what Sakurai is looking for. If she or Tharja got in and were revealed before much of the roster, it would significantly boost the characters that have truly unique move sets (it would hurt generic sword users like Samurai Goroh, for example).
Robin want: 50% (i.e. indifferent)
I'm not that into Fire Emblem, so I don't really care if we get a third rep and therefore none of them make it past indifference with me. But I'd rather it be someone who's not another sword-wielding lord (who probably has blue hair).
If they just gave him/her a sword, I would be really annoyed at them missing the chance to represent something else about Fire Emblem. Because when you play the game, there's a significant number of characters who DON'T use swords, and yet that's all we've seen. There are some other options to do that as well. I would strongly prefer that they make Robin female if s/he is added, since we need more females and there's nothing lost by doing so in this case.
Sonic prediction: 75%
This is a tough one. We don't really know what Sakurai's thoughts are about 3rd party characters in the game. Sure, he said they're special cases... but being veteran 3rd party characters can be called a special case as well. So people's ratings are going to have a bit more variance I think.
Nominations:
Mike Jones x10