They are Dragons but they are the
Energy Trio: "
Blazing White Yang", "
Electrifying Black Yin", and
"Frozen Boundary"
Fire, Electric, & Ice are the only element of ANY BW2 artwork that have been pronounced in any way shape or form. How much of a difference does it make that Dragon is first in it's typing? They learn far more Fire, Electric, & Ice moves respectively than they do Dragon Moves by Level-Up alone. At ANY point was Fire, Electric, & Ice mentioned as being a "secondary" typing, I'm
pretty sure that's just a "
fan term".
http://www.pokemon-movie.jp/trailer/index.php
If we give the movie any credit, Kyurem doesn't actually fuse with Reshiram or Zekrom as much as it just saps them of their energy. Don't think of these as "fusions", think of them as the Fire & Electric forms of Kyurem. Kyurem absorbed BOTH Reshiram & Zekrom's energy in the movie so it can probably change it's form at will similar to Deoxys. (
Kyurem IS from space. Not sure if coincidence or...) There aren't 2 Kyurem. It didn't possess Zekrom & Reshiram. They're never seen together, it's just editting that makes it look like that until you realize that
White Kyurem is attacking in the day-time while
Black Kyurem is attacking in the night time. I'm sure they've went to GF for the facts so I'm willing to bet my money that the movie is a reliable source as any on this specific matter. So with that said:
These are forms of Kyurem. They are not the Ice forms of Reshiram & Zekrom.
So stop thinking like that. You're making it a LOT more complicated than it rightfully should be. While nothing's confirmed, I consider them
Ice Kyurem, Fire Kyurem, & Electric Kyurem. It makes a LOT more sense that way from a design perspective and especially a concept perspective. It makes NO sense for him to keep his Ice/Dragon-type. He may keep his Ice-typing or he may keep his Dragon-typing, but not both. I'm leaning toward Dragon but that's just me. My point is that the evidence for a Fire or Electric-typing is just too staggering. The only evidence otherwise is a flash animation with an icy background. That argument wouldn't even hold up a thin sheet of paper.
Oh and how is having two completely different Fire/Dragon & Electric/Dragon Pokemon sooo much crazier than having THREE Ice/Dragons with the same movepool minus one attack? Sense; please start to make it, Smogon.