Let's talk about Rosalina & Luma
Luma Shot
This is their Neutral Special. The more you charge it, the further Luma goes. It is also used to bring Luma back to Rosalina.
Luma's Movement
The moves shown here are Neutral Special, Neutral Air, and then jabs into a finisher.
Sakurai said that Luma wanders on its own, which makes it seem like you don't have control over Luma's movement when Luma is far away from Rosalina. It also seems like Luma's position doesn't affect what moves it does. As long as Rosalina does a move, Luma will do the same move any where.
Regarding Luma's random jumping.
NotLiquid thinks that Luma jumping has to do with Luma trying to be at the same height level as Rosalina. I think that is right. The first GIF/WebM in this post shows it doing exactly that. The second one shows Luma doing that as well. Here are three more examples:
While Rosalina doesn't make Luma jump when she jumps if Luma is far away, she does influence what height Luma wants to be at.
Some Attacks
Here are some more attacks:
2 Jabs, Side Tilt, Up Smash, and Neutral Air
Also, something to note here is that Mario's cape doesn't seem to make Luma turn around here. It seems Luma isn't affected by the cape.
And even more attacks:
Back Air and Down Tilt
More Special Attacks
So Sakurai reveals this:
Side Special = Star Bits
Up Special = Launch Star
Down Special = Gravitational Pull
It's all stuff we've seen before, but we do see what the Gravitational Pull seems to do with a "traditional" projectile here. Lucario's Aura Sphere seems to go around and then disappears into Rosalina. It could be possible that the Aura Sphere can still do damage when it is going around like that and if gotten a kill like that, maybe it would count for Rosalina. And we see it has a pretty large range.
Also, it should be noted that Rosalina doesn't seem to be "flashing" which indicates invincibility when grabbing the ledge.
Now there are 3 questions left with the specials being revealed. Which one summons the Luma? It would probably be either the Side Special or Neutral Special since there seems to be no use without having a Luma. It could possibly be both. I also think it can't be summoned in the air.
And if only one of them summons the Luma, what does the other attack do when the Luma is missing? Is it just useless, or does it do some damage?
And lastly, what is Kirby's copy ability going to be? I'm thinking it will be the star bits attack. But it could potentially work like Kirby's Olimar copy ability where it would pluck a Pikmin and throw it immediately and then the Pikmin disappears. So with Rosalina & Luma, it could summon a Luma, then use the Luma Shot, and then it would disappear. That would be weird if it is the latter.
Power Star
And finally, their Final Smash. It looks cool. It seems some of the stars coming out of the big power star don't seem to bounce all of the time which is a bit odd.
I thought their final smash would be some sort of star bit storm lol.
Rosalina & Luma are very interesting since they are pretty unique. I'm just curious as to how Luma's movement is going to be handled. If it is AI-controlled, I hope it isn't stupid.
