A bit of a prologue --
So I was playing online recently with Rosalina & Luma and I was playing against a Marth (with Peach at first; it was a close finish but I lost) and it was a very easy win, however, after I won the person I was playing against switched to (Little Mac before) Megaman and it was pretty difficult. I managed to lose twice until I switched to Sheik and beat him.
-- End of prologue.
This player was very good with Megaman, and even though I'm winning many matches, he seemed to be a good counter to Rosalina & Luma. His projectile game can be hampered by GP (Gravitational Pull), but since he's so short (and you don't GP), his projectiles tend to go under Luma and hit Rosalina, or he can jump and hit her with projectiles (she's a very big, tall target). However, with that said, when you play defensive against him (spamming GP while he's campy with projectiles), you can get him to come to you and punish him. I could have done this to win, but I'm still getting used to the game.
Can we create a ranking match-up(tier) list for Rosalina & Luma? Well not immediately, but after some time passes.