ohhhh man..... eat steak beforehand, and I hope it goes well. Make sure you come back and post the outcome... and deffo record the matches if you can!! We'd love to see them, and study what worked and what didn't.
At least I would. I can't handle Marth
at all. He hard-counters me as a person, the way that Sonic is reported to have once countered Inui (I doubt it's the case anymore, but w/e).
Here's what one of our wiser Sonics has to say about this matchup:
yeah man i got alot better against marth after fighting dan for so long. another thing u wanna do is outlive marth....and bait alot of f-smashes. the move is highly punishable. up tilt is his safest kill move and u can survive that until about 150 or so. dan/any marth i play always tells me that i dont die. its because his kill options really revolve around u either messing up ur spacing....attacking his shield blindly or well timed f-smashes. and this may sound...super....super....super weird cause every marth will telll u that BF is their best neutral but take them ALL to battlefield. its his best neutral if he can control the bottom platform....but with the up throw u can put him on the platforms ALOT and put him at his weakest point (below him) alot more frequently. also....dancing blade 101...if he goes for the last hit with 10000 little pokes SDI into him as hard as you can. you will end up behind him b4 the move finishes....thus ensuring the f-smash since the move takes 4ever. also do not roll behind dancing blade. u will take an up-b. also if u r shielding dancing blade and u SUSPECT the downwards one is coming....grab. the downwards dancing blade is able to be grabbed inbetween the 3rd and 4th hit. the upward one as well...the regular one is not. other sonic players will tell u its all about tilts and w/e....but marth is a characters BASED ON SPACING and TRAPS....sonic really loves to **** ppls spacing and up-p out of dtilt traps or walls that he cant find a sensible way around. so really running is the best offense.
My own thoughts (but I'm fairly scrub):
Marth's moves are fast;
some of them have punishable ending lag. Good Marths won't be swashing away at nothing, so you'll have to approach, or
convince him that you're approaching, which is hard.... side-B shieldcancels get old very fast, and ASC shieldcancels are tooootally punishable if they get in range. Try not to spindash a lot. If you're shieldgrab-happy (as you probably should be, as a Sonic), this is really dangerous... Marth will be spaced to tipper, and you really can't punish him at that range; you certainly can't grab, and clashing with a Marth does indeed mean he gets a free dtilt, afaict.
Boxob's suggestion about dash-attack is actually a good one, at least when he's at mid-high percents... it works really well at punishing anything the Marth does, but you prolly want to run away after. Either get in at very close range + jab/grab, or stay awaaaay. Dash turnaround pivot cancel stuff is good for faking out approaches while carefully staying just out of tipper range.
Spotdodging near Marth means you eat a dancing blade. Learn to (S)DI it to get out!!
Never get on a platform anywhere above a Marth, it's insta-tipper
If a Marth is really high and you want to Uair juggle, remember that his Dair has
crazy ending-lag, so if you can bait that you win. More likely, the Marth will try to airdodge your attack, and/or Nair instead.
Marth's recovery always looks to me like it
should be really punishable, but it's actually very good..... but it can be very predictable; it's a guessing game about when they'll finally do their up-B. If it doesn't sweetspot the edge, we have a good chance at punishing it. Marths can ledgecamp very well, it's tempting to dive in with a Bair or Dair but that doesn't work very much since their up-B has invincy frames and tends to stagespike us in exchange. Dropping springs is safe and can mess them up rather often, IMO. I hope you can instant-edgehog, because that's your tool when a Marth doesn't sweetspot the edge; Sonic's fast enough to pull this off way better than any other character, and he might not expect it.