It's baffling that people think Sheik is going anywhere, it was understandable during Brawl days, when we got the new Zelda and it was thought Sheik would be gone because she wasn't in Twilight Princess. But near the end of the updates we indeed got Sheik, in her new updated look based on the concept art, with Zelda keeping the same look, it's pretty much a given that Sheik is still here (even so, Sakurai would have just BS'd a new look for Sheik anyway). Sheik was revealed far after Zelda was in Brawl, this is simply the same thing, Sakurai screwing with us. The Phantom obviously isn't part of her moveset, even without the fact that she pulls off the same pose without the Phantom, the thing just does not mesh with her art style, when Sakurai kept Sheik in Brawl, he made sure she matched Zelda's look. Why would he keep Zelda the same and then just throw in a random Toon Phantom for one of her attacks? This makes no sense in the slightest.
Diddy is really starting to grasp at straws over Impa here too, there is no evidence that she is in that new Zelda spin-off (may I remind you that the game will have little to no bearing on Smash Bros?) other than a really blurry picture of a person that slightly looks like Impa. Even if said person turned out to be Impa, it is not clear at all if she is playable or not, no one other than Link has been shown to be playable, Diddy is stating theories as though they are facts, we simply do not know if Impa is in that game or if she would be playable. As much as Diddy will keep trying to say that Sheik isn't in the game, remember, Diddy isn't Sakurai, he is not making the game, and Sheik will be in whether he likes it or not, his wining will not change anything. One person disliking something means absolute ****.