Well, I was browsing Know Your Meme's Smash gallery and got myself a new avatar and sig. Pretty manly, if I do say so myself.
Tetra seems most likely as she is the most popular Zelda character in Japan I believe. Plus, she was planned for Brawl so...
Tetra confirmed!
Naw, I only thought Tetra had a chance if she was a transformation for Toon Zelda, but now that transformations are gone, I don't think either of them stand a chance. I don't think we're getting a new Zelda character this time around, Ganon's Minion was the most likely choice, with Ghirahim as the default. It would explain why Toon Link got in, he couldn't be replaced (or it could just be Sakurai's idea that "the younger Link is the true Link"). Either way, he's my main in Brawl, so I'm certainly not complaining.
If we ignore the leak, Shulk, Ridley and Mewtwo are really the only ones I'd put money on. At this stage, I don't really care about newcomers, veterans are all that matter to me.