Anyone in this thread speculating how good a character will be before they've even touched the controller is out of their minds, just saying. It's a new play style to smash people, but it's not unheard of. It has its strengths and weaknesses. Now it's just up to them to balance it out right.
Back to the thread at hand, I think what we're mostly missing would be her A tilts, back air, neutral air, FS, up/down throws, pummel, get up attack, and ledge attack. There's still quite a bit unknown about the Luma's moveset, considering we've seen so little (USmash, star bit attack, jab combo, quick dash, ect). I would like to point out one thing though. Some one mentioned that the Luma would mirror rosalina's move (the forward throw > luma usmash combo from trailer was a good example), but I don't know how correct that is. There are several points where the luma does nothing while Rosalina is in action. A simple example would be where she's charging a forward smash with the red luma behind her that proceeds to get knocked out. This alludes to either you have more control over luma than simple mirroring, much more like standard shadow characters, or that there is a way to desync their attacks. Just something I thought I'd point out.
@Jao It is possible, but the choppiness of the animation between the crouch and the cursor almost confirms it to be her down b, though I won't try to confirm without more evidence. I can understand your qualms with Kirby copying the Luma skill, but there are 2 answers to that. 1. Kirby will summon a Luma and will have a way to control it all it's own, making Kirby vs. Rosalina the most ridiculous match up in the world. 2. He gets some unique action with Luma, similar to how he handled the pikmin pluck from acquiring Olimar's ability in Brawl.