I LOVE ROSALINA.
And coming from a Peach main, I'm happy to have her in my roster instead
Some Suggestions, if I may:
Neutral B is really useless D:
I feel like it should reflect projectiles or counter or something useful, preferrably the former. It's basically just the old nair with a larger hitbox.
Speaking of Nair, this new one raises Rosalina in the air a good bit, and can be spammed for infinite recovery, which is reallllllllly broken. Perhaps you could make her nair do exactly what her current Neutral B does, and give her an entirely new Neutral B
....Or just lose the height gain it causes.
Side B is my favourite, however, I feel like it's a bit overpowerd when spammed. Maybe reduce the speed at which you can fire them off?
Also I've noticed that if you use it while dashing towards the edge, she does a sort of glide off of the edge and keeps moving outward for as long as youre throwing stars. Upon stopping, you'll immediately teleport back to the edge of the stage. This might be broken, but it's really fun for mindgames
Down B seems really inferior to Side B. Not sure what to suggest here.
Up B on rosalina just seems kinda dull, though I understand if you don't want her to have a completely new moveset.
Keep up the beautiful work