We can't really compare the Kyurem from the games with the Kyurem from the movie. The anime doesn't always follow the same rules as the games. Just look at how Deoxys changes formes in both of them. In the anime, Deoxys can change freely, while in the games, it originally depended on the game it was on. Now, you need to interact with meteorites to change its forme. Just because Kyurem appears to be able to change formes at will in the movie, doesn't mean the same will happen in the game.
Also, I don't think that we got 2 games because there were 2 formes, nor do I think that we got 2 formes because we there were 2 games. I believe Game Freak planned this all along, introducing 2 new formes for a Pokemon in 2 sequels. 1 isn't a result of the other.
As for the name of the attacks they are "Fusion" because like the Oath attacks, the two attacks can "Fuse" in a sense. If one is used before the other, the Second attack grows in power and changes animation. Their original name is "Cross".
I was wondering if someone was going to point this out! I couldn't remember what the original names were, but I knew they weren't "Fusion".
Lol, how can you imagine tubes coming out and hiding in the sprite loop? That would look ridiculous. More of that they don't have those tubes in movie trailer, so it's clear that this time it's real Overdrive mode, not just sprite animation.
I don't think that would look so ridiculous. Darumaka's animation shows it pulling its arms and legs back into its body and appear to fall asleep for a second. Look close at the original pictures of the "overdrives". Other than the tubes and glowing, what is different? Nothing else. They are still bascially Black Kyurem and White Kyurem, not a new forme. Here's both pictures:
See? Same formes, even pretty much the same art, just upgraded a bit. We can't compare this to the Shadow Pokemon because they didn't physically change and the "high pitch" of emotion was triggered randomly. Also, Darmanitan's Zen Mode is also a forme change, so we can't compare that either. Zen Mode is triggered through loss of HP, not emotional stress, and actually looks physically weaker. But these "overdrives" look very powerful, so it wouldn't make sense for a Pokemon to appear its most powerful when it is close to defeat. Emotion isn't a stat, and one could also say that simply being in a Pokemon battle is enough to trigger intense emotions in a Pokemon. (see Reshiram's and Zekrom's overdrives)
I still say that this will probably just be part of the sprite animation. Until further info comes out, this makes the most sense.
It seems that in Black 2 Kyurem will be able to switch only to Black Kyurem after fusion with Zekrom's energy and in White 2 only to White Kyurem after fusion with Reshiram's energy. And it's almost certain that those form changes WON'T be only in-battle because they are MASCOTS and mascots are never only in-battle forms.
I agree with you. It would make little sense to have 2 different formes of the same Pokemon as the mascots of the games if both formes are available in each game. I think the formes will be version exclusive, or at least the method of obtaining the formes will be.
Seeing as in the movie Kyurem can freely switch between them, I doubt an item is required. There can be an item like Rotom's or Shaymin's or a hold item like Giratina's, but based solely on what has been said and shown, Kyurem can freely switch. Again, Movie said Kyurem already has their powers. It got them at its birth.
Again, we can't always compare the anime to the game. Personally, I feel like the formes will simply be unable to be changed once you obtain Black/White Kyurem since they are supposed to be "separate Pokemon". (However, Shaymin used the Gracidea Flower in both the anime and game, so an item might be possible.)
But I have to disagree with the "had the powers at birth" thing, in a way. Kyurem are supposed to be able to absorb the powers/genes of the other dragons, so in theory, it could have possessed this ability since its birth. But I don't think that means it was born with the other dragons' powers already available to it without needing to absorb them. I guess what I'm saying is that Kyurem isn't born with Reshiram's and Zekrom's powers, but it's born with the ability to absorb their energy. (same difference, maybe?)