Well Ganondorf did poses Zelda with his newly learned Twilight powers and Zant possessed the Stalord with Twilight magic. And Zant changed forms slightly when he made himself giant in the battle, and remember in the early part of the game when Midna changed to look like llia, plus she can turn in to Link's shadow at will.
I believe he used his power from the Triforce of Power to do this, Not his Twilight Magic...Infact I don't remember him gaining any Twilight Magic, He just uses the same means as Midna does when she uses a portal to take over a body. Zant never possessed Stallord either, He just reanimate's him using his power most likely granted to him by Ganondorf.
Thats not really full transforming when he makes himself bigger and smaller, He just makes himself a different size. Midna can transform into Ilia because Midna has the true power of the Twili so unless Veran in the leader then I doubt it. She doesn't really turn into Link's shadow at will if I remember correctly, She just hides in it so that others can't see her. Infact I think she tells you once you first leave the Hyrule Castle after Meeting Princess Zelda.
True Ganondorf did do that, but you have to remember that some of his powers comes from the Triforce of Power and also recall that Zant orginally did not have those abilities. They were given to him by Ganondorf. I think (although this is just speculation on my part) that in a sense, Ganondorf's power from the Triforce enhanced the Twilight magic to allow him and Zant to do those things. Thus they couldn't do it originally before they began to share powers.
I believe that this is correct, Zant gained pretty much all his power because Ganondorf granted him power because of his promise that he would help Zant for helping him to get out the Twilight Realm and to Hyrule.
Although I do disagree with the fact that Ganondorf simply enhanced his Twilight Powers but its easily possible. I think that because he isn't part of Midna's bloodline that he holds little magical powers at all so Ganondorf had to grant him several. Well, there are powers that it would seem that Zant may have knew before like summoning Twilight Portals where ever he likes.
And Yes, Midna did change forms during that point, but I see that as just an illusion trick. Also possibly (another speculation here) it could just be that she could change into other people and not beasts, seeing as the only time that she did change into a beast in the game was with the Fused Shadows.
I agree with this statement as well, I believe that Ilia may have just been an illusion that Midna made with her power, After all it doesn't seem like a hard task to do and it isn't actually possessing someone, Just imitating their looks. I doubt Midna can transform into beasts by will or with her own magic either, If she could she would have done to defend herself whenever Ganondorf/Zant forced her out of the Twilight Realm.
As it stands I have little knowledge of Veran but I have enough Knowledge to believe that Veran doesn't belong to the Twili Race, She does share certain qualities that they do but it doesn't mean she is one of them but hey, I could be wrong but I'm doubting it.
