User blog comment:Matt Hadick/Super Smash Bros. for Wii U and 3DS Tips and Tricks/@comment-8182065-20141218040119

Rosalina: Not only is Luma handy for adding up damage with Rosalina's attacks, they can be great for blocking certain powerful attacks such as Charizard's Flare Blitz; just remember they will disappear after getting hit too many times.

Make great usage of her down special against opponents with a lot of projectile moves. She can pretty much deflect a great variety of Mega Man's moves (up air, down air, neutral attack, neutral special, side special, side smash), and can make quite the fearsome opponent.

With proper positioning (pretty much opponent must be above her with good timing), Rosalina can trap opponents in the center of her Final Smash. They will be unable to escape and should launch off the stage with +200% once the Power Star explodes.

On the last one, I've managed to do it twice. First time on Kirby, Tomodachi life stage, they rage quit afterward. Second time on Captain Falcon in the Unova Pokemon League stage. I believe you might be able to perform a similar effect by throwing opponents in there, but there is some potential for them to get loose.