oh man I'm about to have some fun.
1) aiight, good to know. what percent does it start and stop working at?
The % range is very large, probably starts as low as 60% and goes all the way to like 120+% (maybe even higher). It doesn't start to KO til probably 100%+ (before the throw) give or take a few % depending on the stage, the positioning of where the grab is landed and DI.
Realistically tho, Doc will not be landing grabs on Marth too frequently, and he needs to land a grab within the % range where it connects and KOs. Most of his kills will be from Dsmash and edgeguards.... unless the Marth is really bad at the matchup like almost all marths are, at which point you'll be seeing a lot of dthrow -> fair.
2) luigi definitely doesn't.
Aight I'm only doing this once, I hate reading long posts and I don't like making them.
I'm curious what really good Docs/Marios/Luigi's you've played and beaten to make your basis for some of your matchup ratios. Having played all these matchups many times on both sides (minus Luigi vs. Marth as Marth) with many of Tristates quality players (I can list them if you're curious) I genuinely feel Luigi does the best out of all three. Am I saying he wins? No. Am I saying its close to even? No. It's definitely at best a 60:40 in Marth's favor.
Marth beats all three of them by getting them above him and ****** them as they miserably attempt to come back down to the ground, and then he exploits all three of there terrible recoveries in pretty much the same way.
The one thing Luigi has is the most range of the three, with the best spacing on the ground with wd ftilt (so he doesn't get zoned out as easily) and probably the most practical aerial moveset of the three for wracking damage up real fast and getting Marth offstage. And the best part is he doesn't need a grab like Doc to setup combos or finishers, and he doesn't need to worry about perfect spacing like Mario to get Marth offstage.
I'm definitely forgetting a lot, but that's what I got for now. Anyone else can feel free to add on to this.
3) and who the **** are you to say that? some random doc scrud?
You're in no position to call me a scrub. You live in one of the worst regions of the country and you don't even place that well (I look through all the tourney results every sunday). Not to say I'm amazing or anything, but I tend to place 9th or 13th out of like 60+ people at the regionals in arguably the best or 2nd best region in the country and I only lose to the really nasty players and it's never free (my last set with chops every game went down to last stock last hit). I also live 10 minutes from all the **** NY smashers (PC, Vanz, jesus, chops, dj etc) and play them on a weekly basis.
And I don't just play Doc, all of my top tiers are really good and I play a large majority of the cast at a high level. Come out to ROM3 and I'll MM you any of my characters vs. your Marth for however much you want. We can discuss more over aim if you're interested.