Apparently Toon Zelda was intended to be in Brawl, but was scrapped due to the lack of a Toon Sheik design.
Darn, I wanted to be the one to give that information! I should have woken up earlier.
![tongue :P :P](/forum/styles/default/xenforo/smilies/theme_icon3.gif)
Yes, Toon Zelda has data in the Brawl disc, she was, a one point in time, considered to be playable in Brawl.
I would not like to see a playable Toon Zelda or Tetra character. Like ALIT said, there are already too many characters along the lines of being semi-clones of each other. The fact that there were several literally copy-pasted characters in Melee, and the developers nerfed these characters movesets to difference them from their influences (or removed them entirely) shows that Sakurai is now against the thought of clones. There was a rumour before its release that Brawl would have no clones, and despite be unbelieved at first, it turned out to be somewhat true. He would be silly to add another clone character and not create even further differences between these already existing pairs of characters.
"But what if Toon Zelda isn't a clone?" Well, if this is the case, I still think she shouldn't be a playable character. Series in Super Smash Bros. really shouldn't exceed four characters (with the transforming characters not counting). With Link, Zelda, Ganondorf and the younger Link many hope for, I personally feel that's enough. =\