As far as whether or not "Black" Kyurem and "White" Kyurem are forms or separate species, Serebii.net reported the following:
Edit: Junichi Masuda has revealed the names of Kyurem's new forms via his Twitter account. The forms are simply called Black Kyurem & White Kyurem, though he interestingly lists them as seperate Pokémon
I think that "Black" Kyurem and "White" Kyurem are not entirely separate species, but not that much forms of Kyurem. Rather, I see them as
in-between species. I theorize that the are very similar to forms, but they, in the sense of the Pokemon world, aren't entirely forms. Rather, they are
fusions of two different species, something never been done in the main series games. And I can't say I'd expect something anymore, because the reveal of Pokemon Black 2 and Pokemon White 2 came by total shock to me, but I could see that they could introduce more "fusion forms", but rather of a Reshiram-Zekrom fusion, and/or a fusion of all three.
These games may
totally change the nature/physics/chemistry/whatever-you-want-to-call-it of Pokemon. Many people have suggested that these new Kyurem "forms" could have a triple typing. While I somewhat doubt this is possible (the tying of Freeze Shock and Ice Burn suggests that Kyurem keeps at least its ice-typing upon transformation/fusion/whatever), this would be the
only case where triple typings are accepted, as they are demi-Gods/legendaries in the Pokemon world and aren't acceptable in the metagame.