I hate to rain on a parade, but I disagree with all of the OP's points
1) Zelda not being in the demo's prove that sheik is in.
I'm sorry, but no it doesn't. It's true that they appear to be hiding the existance of Sheik as best they can, but why does that prove she is in it? I mean, if they did remove Sheik, then they'd still keep it a secret. So her not being in is still just a big question mark.
2) Melee stages
An interesting explanation, but I have a better one. Sakurai wanted to put in old stages and he's not going to say "Well, I really like this stage, but since we don't have the exact character for it, it's out." If Onette was turned into a new stage, then you'd have an argument, but as an old stage, it's simply an old stage.
3) Melee Team
He could just as easily be based off of a number of other characters such as Snake or some other character we haven't seen yet It's also possible (not likely) that they have their own moves.
Yeah...I do agree on your points as well. It's pretty much an opinion. For Zelda, yeah, they'd hide it if they removed Sheik...but not having the FS revealed for so long must have some other secret involved too. If it was just Zelda in that FS, they could have revealed it way before but there's something that is keeping Sakurai from revealing the FS. Other characters have been revealed even before her.
For Ness and Ridley, those are long shots. I myself admit that.
For Capt. Falcon and AC Villager, hmm...physique looks more like them...so yeah. Don't like to discuss that point anyway.
