SpiralGalaxies
Smash Lord
Yikes. I never though the matchup would be so bad.Luigi is actually terrible at getting in without fireballs. He has some of the worst baiting mechanisms in the game, due to his abyssmal airspeed and acceleration/deceleration, and even further his ground game means very little. Fireballs is actually the only thing that gives his neutral game some worth, because they come out so fast and he can act out of it so quickly that the damage and hitstun behind it is worth it. However, Luma exists so they're blocked. He would actually appreciate Mario's fireballs even if they have a longer recovery.
What makes Luigi so good is his quick grab and throw game because he can just pile on damage in immense bursts, and when he gets going, he gets going. However, Rosalina is light and floaty, meaning she can DI out of his strings, and Luma exists so she can reliably combo break him or even break the grab in general. Even further, Luigi's B-throw does not launch Luma at all. It just makes her flinch. So while Luma is in play, grabbing Rosalina takes an obscene amount of effort. And when you can't grab, Luigi's weaknesses as a character becomes really, really apparent.
Luigi's combo breakers, N-air and Cyclone, also does absolutely nothing vs Rosalina's U-air, so he gets juggled for free.
Luigi is essentially a Ganondorf in this MU and I'd even go as far as to say Ganondorf has a better MU against Rosie than he does.
Thank you for responding though! <3