I'm sorry, but as far as I'm concerned, Cloud, Geno and Sora are in the same boat. There's plenty of more worthy characters that SE could bother to sign off on to use in Brawl, such that they wouldn't have to utilize these guys that just don't come off as iconic as a number of other characters in SE's grand pantheon that have much more of a "Nintendo" air to them.
If you want some one more recent, there's the likes of Monteblanc (FFTA), Neku (It's a Wonderful World), or even the new guys from the upcoming DQ9 and FFCC Wii games would be ok choices, even if they were meant more to advertise and promote than anything else.
But in the classic model, you got the likes of Terra, Celes, Kain, Cecil, either of the Figaro Bros., Crono, Magus, a wide slew of Dragon Quest favorites, or even generics like a Black Mage and a Slime combo. Any of these guys would be both iconic, as well as would do more to resonate with the Nintendo demographic than the 3 aforementioned characters.
Cloud = Is definitely more of a PSX-generation personality, plus he's only appeared in one game on the GBA...and as a bit role at that.
Geno = Caters to a relatively small hardcore fanbase. Hell, Europe has no real reason to like the character, since they didn't even get to play SMRPG.
Sora = Much more of a PS2-generation personality. Only one game on the Nintendo hardware thus far, and it would still be more of a thing that his Disney roots would probably bring an unwelcome flavor to the party. If you really want some one like Sora in this game, again, I would suggest devoting your energy towards IaWW's Neku.