Roy was advertisement, alpha n00b. As for your spam about "No Anime Characters", guess what, who cares? To our knowledge the chances of an Anime/Manga character is 0%, but that doesn't mean Sakurai can't change his mind. As for Leif...who? Still a mystery to me. If you need to provide a full video link, then more than likely, the character isn't really well known. Is he another advertisement for a Fire Emblem game? I wouldn't double the ads just because it happened once.
Anyhow, for third party choices, I personally wouldn't mind Nightmare or Fighter(FF1, and yes, that's his original name). Nightmare would be Bowser with reach, but less speed and no projectiles. For the most part, Bowser could easily beat him, thus, making him no so broken. Fighter may be generic to a point, but he can also wield legendary weapons, now can't he?
Ganondorf with a sword and rounded-out move list would be nice. As for Golden Sun characters...I'd still rather see Mia etc. for more spellcasters.
Lyn isn't a bad choice either, as female swordsmen...or females in general, are needed to round out the game.