Deadjames, I can tell you right off the bat, there's a really important difference between Melee Luigi and PM Luigi: Floatiness. The difference is, in one short hop, you can bust out not one, but TWO aerial attacks, provided your first attack isn't Nair. He's like...a floating battleship of death that moves around at blistering speed on ground. As far as the Wave Land Fireballs of awesomeness, you have to do the input REALLY fast. Like, I literally flick my thumb across from X to B while sorta skipping the A button. Hard to do? Hell yeah. Swagtastic? You bet your sweet ass it is. As far as getting back to stage goes, thanks to the previous said floatiness, one is able to use the following to hitstun the enemy/cancel projectiles:
Fireballs
Fair
Uair
Tornado (My favorite way to deal with obvious projectiles off stage like Link's bow)
Missile (If you're so low that you know death is unescapable, try getting a Green Missile charge)
I never have problems getting back, especially since I've got the sweet spot for the missile and the height for just barely grabbing the ledge via SJP or Jump down pat to avoid being spiked with say Falco's Dair.
You say Dtilt isn't viable, but I'm telling you, that thing is MADE for shields, like, it safely pushes you away from the opponents while eating a good portion of their shield. Provided of course, there was a shield to hit.
As for the Dash Attack->DSmash, I agree if they're grounded, but I use it sorta like an Anti-Air, if I'm close and I predict they will jump (which they love to), it catches them in the air nicely...but only for higher percents. I've personally yet to have seen that crouch canceled under those conditions.
Boomer: Don't **** with Fox's shine, lol. Just Dair the son of a ***** til he's off stage (followed by more Dair).
MrDoubleT: Luigi already is already really fast on ground, last thing he needs is to be able to WD in and HOLD DOWN PRESS A TO WIN. As I said in regards to Deadjames, that thing is made for punishing shields in hopes of breaking it (or safely retreating).
Dear God...reduced lag on Fireballs... Luigi wouldn't even have to approach...he'd create a walls of fire. He already can give the medium to slower cast a hard time approaching without taking damage with his horizontal, slow moving, Wave Landable fireballs. He'd become the ultimate Defensive character.
Increase Sweet Spot for the Shoryuken? It's REALLY easy to get in already...doing that would make being next to Luigi=you're dead. It's tricky, but you CAN use it as finishers for DThrows and Aerial combos. Eli has shown this, and it's what brought me towards maining him in the first place.
As for the misfire (Greenie/Green Missile), the rate it happens is fine enough. It's not supposed to be an attack that's pretty much guaranteed to work out (cause then you can just Dthrow->Side B), it's supposed to be either a gamble or guaranteed followup if charged.