50:50 sounds good, maybe maybe MAYBE 55:45 Marth imoimo.
Marth has to play very very patiently, possibly even to the point of extreme frustration (From my experience from playing against Marth).
At the same time, DDD has to be equally careful. Tiny openings in DDD's defense equal massive ****, especially from Marth, who has the speed and moves to put the hurt on DDD.
It's funny tho. DDD on defense faces a lot of pressure from Marth on offense who is also under extreme pressure to watch his spacing.
(Pardon me cuz I don't know a terribly great amount about this particular match-up, particularly Marth himself)
Marth is probably one of the best characters in the game to play a spacing game against DDD. Doesn't mean it's easy tho: A slip-up equals 15%-35% depending on where you were grabbed. Just know if that there are any Waddle Doos along the way, or if there are any walls, expect a brutal beating - highest CG combo without walls that I've ever seen dealt over 117% (!). NEVER stop mashing buttons trying to get out of the CG - the DDD might be stupid and try to jab you at low percents or more than once at any other percent.
Marth will want to focus on punishing. I think it's the only way to play a good DDD. Marth has the effective tools for that - speed, very quick attacks (DANCING BLADE ARGHAGRHAGR) and 'gtfo' moves (Dolphin Slash), GREAT range and spacing, aerial DI (Which is vital in this match-up), and a very good pressuring game. Above all, tho, Marth has to watch his aerial momentum, and his movement in general - Marth does not want to be anywhere NEAR DDD for more than a split second. Please don't SHAD near or airdodge into the ground near DDD unless you KNOW you won't be punished.
Marth combos DDD's balls off. Killing could be an issue if you can't land tippers.
For the love of god DON'T smash unless you are 120% SURE that it will land and/or you'll go unpunished.
Marth is good at forcing DDD to use his upb. This alone gives Marth quite an edge.
Shieldbreaker. But don't use it unless you're **** sure you'll get DDD or else he'll become wary.
DDD has a fair amount going for him as well. DDD can just sit back and toss Waddles all day while awaiting where your approach, which is where he thrives. It becomes a battle of who is more patient - we'll assume that both players aren't idiots. D3 will only toss waddles at a range where he can't be punished, and a good Marth shouldn't be bothered by them (Gordolol). At a closer range, the waiting game begins. D3 creates a wall with bair or he can tempt you into approaching with his SH fairs (He'll just ftilt or shieldgrab you upon landing if you rush). He could also just sit there with his shield up like the ghey penguin he is, which is what he will most likely do.
Getting grabbed by DDD is inevitable. DDD racks up immense damage from this and can refresh his best moves along the way. The CG can also put Marth in two perfect positions for a WoP, which equals a stock being taken if you just happen to get caught. It shouldn't happen to Marth tho, his recovery is way too fast and it's hard to gimp Marth when he has time to respond.
D3's moveset (I honestly believe that D3 can almost match Marth in the air, but they go even on the ground), imho, is incredible, although majority of them are situational. Notable attacks are: Bair, dair, fair, Ftilt, utilt, and fsmash (lol).
Inhale. My fav D3 move. Means that shielding or even pursuing an aerial D3 (Which he should rarely be doing btw) is rather risky. I honestly think that it's the best mix-up move in the game - it's way too good. :] DDDcide is scary. Don't underestimate the use of this move.
That's all I can think of right now. :]
edit: wait a sec is this discussion already done?
