Exactly how I feel about the forms, and maybe they are actually whole pokemon, I mean masuda tweeted that, and while embellishments abound in adverts, gamefreak has never outright lied to us.
iirc, Shaymin & Giratina's other forms were referred to in similar ways. Rotom's forms were certainly presented in a similar way to actual new Pokemon (with the teaser images and the silhouettes and so on).
I think it's just their weird nomenclature.