ThegreatVaporeon1
Smash Ace
Marth still outspaces everything else Luigi has by a longshot. There are a lot of really great Melee Luigis that I've seen switch characters vs Marths that are significantly lesser skilled than them. Marth is definitely Luigi's hardest matchup in Melee. I do realize that fireball is changed, but Marth doesn't really have that big of a problem with Falco's lasers either, which is definitely a more difficult to deal with projectile than the green fireball. Luigi can also edgeguard spacies really, really well, and it's difficult and awkward to combo him with that nair. Keep in mind that Fox also has no shine combos on Luigi, and he's floaty enough to where Falco doesn't get much off of a shine at mid-late percents either.
Shiek is a harder matchup than Marth in my opinion, in both melee and PM.