I'll have a go at this. First, 50 characters is pretty good.
- You have Chunky Kong. I would assume the DK newcomer would be one or both of Dixie and K. Rool, and then Cranky. Chunky does not even compete to those three.
- I doubt that Sheik and Zelda will be separated, they haven't since their debut, so it will most likely stay the same if both return.
- Young Link would be pretty redundant, having three forms of Link on the roster that will most likely stay the same moveset-wise. Not to mention Toon Link replaced Young Link so it'd be questionable why he's there. Then again, a Zelda newcomer in general is pretty unlikely IMO, we have the characters we need for that series.
- Replacing Pokemon Trainer with the Johto Trainer does not make sense. Getting rid of the first protagonist with the some of the most iconic Pokemon is nonsensical. They will not get rid of Charizard, they would never do that.
- I don't have that much of an opinion on Black Shadow, but I'm pretty fine with him being in.
- Fire Emblem. I assume they will be having more content from Awakening (most likely in the form of a playable character). I feel as if Lyn missed her chance but she's plausible, as is Roy. But I feel as if the likes of Chrom, Lucina, and/or Robin will get in before them, or at least before Lyn. Roy is still popular. And I also think a 4th FE character is as necessary as, say, 4 DK characters, a 2nd KI character, and especially a 2nd Metroid character. Then again, reps and whatnot. Still, having 4 FE reps and 1 Metroid (ZSS is debatable) and KI rep is unsettling to say the least.
- Waluigi ain't a Wario character. Sakurai has already given his decision on what Franchise Waluigi belongs in, and that's Mario. Not saying Waluigi is a bad choice, but as a Wario rep, NO. (I also kinda belive that Mario doesn't need any more characters).
- Why Male Wii Fit Trainer? Why does that make sense as his own character, especially when he's already been shown off on the site, he would've had a page up.
- Felix and Andy... I don't even know who Felix is. But yeah, put Little Mac in there! Replace Felix with the Big Mac. As for Andy, someone like Shulk, the Miis, or a rep like Lip or Takamaru will get in before him.
- You already have Goku as your "dream choice". So yeah.
Now your cuts are Lucas and R.O.B. Despite loving him, I can kinda understand Lucas being cut, but R.O.B. has no reason to leave. At all. It's the same when people were cutting G&W pre-Brawl. The excuse people have for cutting R.O.B. would've kept him out of Brawl.
Overall, could use some work (unless this is a dream roster, if it was then I wasted both of our times). Welcome to the forums by the way.