everyone keeps talking about "exploting luigis mobility" but like
it's been almost a year since release
the luigi gameplan has kept relatively the same
and it still works
You'd think by now that someone, anyone, would be doing this if it were so true and easy
but it's clearly not, it's incredibly clear to me that it's at this point pretty much fruitless because there is no mythical exploit to his weakness, he has the tools to cover that weakness
maybe, just maybe
Luigi is actually good
But hey
THATS JUST A THEORY
Luigi's mobility issues (and weaknesses in general) are somewhat overstated.
His walk and run speeds are averageish, but his initial dash is one of the best in the game; for a moment when he's using his initial dash he becomes faster than the majority of the cast (I would imagine his traction has a lot to do with this). There are only a few initial dashes I would prefer to have over Luigi's, and one of them belongs to Fox (lol, you know you're not bad in a mobility spec if you're being compared to Fox, unless it's horizontal drift speed), and that too only because of the faster init animation.
Add to that his amazing jab and fireballs, and the random Cyclone mixup (which is particularly effective when you are trying to weave around his initial dash), as well as the fact that he has the 2nd longest perfect pivot in the game (something which has been underutilized, though Luigi's tilts aren't quite good enough to make the most of it), and Luigi has good, perhaps even great, mobility on stage.
His really poor stat is airspeed, game-worst next to D3, but what does airspeed affect? Ability to get followups and ability to avoid damage. Luigi already gets tons of damage from advantaged situations; he even has a KO confirm off of d-throw. He definitely doesn't miss the ability to chase opponents (if he could, that would be hilariously ridiculous; just think about getting frame trapped into Luigi up-smash while landing).
As far as avoiding damage, his floatiness enables him to aridodge close to the ground without punishment. Being floaty is actually often
good in disadvantage, not bad (though with Luigi's combo-breaking n-air he would probably prefer being a fastfaller since the up-tilt strings wouldn't bother him too much if he were, and he'd get better neutral mixups), and he has the n-air of truth (12% damage?, frame 3), and Cyclone mixups. Luigi would definitely like better airspeed for getting out of air traps, but he's not one of the worst characters in disadvantage, period. That title belongs to the likes of Bowser (or even Falcon).
He's not bad offstage either; you always have to respect airdodge -> Cyclone gimps unless you have a massive disjoint like Rosalina d-air because you could lose your stock, and jumpless Cyclone in particular is great. The difference between Luigis who can JC and those who can't is massive; his recovery jumps several tiers with mastery of mashing. Edgeguarding
Ness is easy. Edgeguarding Luigi is much harder.
Luigi is easily a great character. He doesn't really have weaknesses that are apparent unless you are playing one of the characters who exploit them by design (as in, his weaknesses are matchup-dependent). His reward is so massive that disjointed spacers like Ike and Marth probably don't beat him even if they fare decently after the patch buffs, considering that they have to keep him out 2 or 3 times for every time that he gets in.
That said, he does lose pretty hard to Sheik and Rosalina, which may keep him out of the competitive spotlight at nationals. At the same time he's one of the only characters to have clean advantages on Mario, Diddy, Ness, Fox, and Pikachu (characters with otherwise great matchup spreads), so he won't ever really fall out of the metagame.