I was just thinking the same thing, here's what I posted in another thread:
"So, as far as Rosalina's moveset goes, what is the general speculation?
I'd say her Up-B is the star move in one of her pics on the site, U-air is definitely her galactic flip-kick. (made that name up) B move appears to be Luma summon/swap, Down B as her reflect/attract move. Send Luma is side/up/down smash moves, and grab is obvious... that leaves tilts, side-b and jab unknown. Side note, different Lumas appear to have different properties, yellow is close quarters combat, Little Mac style, while red appears to have a Waddle Doo like attack, white and green are yet to be seen in combat... that's all I got."
Since you mention it, the green Luma could be a reverse Luma, which would be cool. I don't think her special change, but rather the different Lumas attack differently
Red = ranged
Green = reverse
Yellow = melee
White = ? (got shot in the face, but that was it)
Blue = ?floaty? (did a strange looking jump her Up-B with her, but no combat)