I've said this around 5 times now, but you are guaranteed a side-b if he does a rising sh fair, it's given. It takes fast reaction but you can absolutely get it between the fairs of ash double fair. Then uair, techchase, edgeguard.
Won't that only work if he whiffs the fair? Usually, I would need to shield it, unless I read it and use the side - b to pull back and dodge it.
Edit: or its that what you meant, reading the first fair, and using the pullback to dodge it?
Powershielding is under-practiced/focused on. Think about how cool it would be if you could dash oos or jab oos. Well after a PS, you can. Know marth's hitboxes and try to do this. Once you have it semi-down you can read when you'll get the PS and input the appropriate counter.
Powershielding is like, my special ability. I get it more often than most people I see, but you really need to read it to make full use, and I'm still not consistent enough for that. I've done ps-jab once intentionally and it was beautiful.
Good for shield grabs though. Maybe that's why I still have such a bad shieldgrab habit, don't get punished as often as I should (except for spacies of course, makes me sad when my ps->shieldgrab still gets shined)
Other advice:
- marth's fullhop fair is not safe on your shield (you can hit him with uair oos)
- side-b is good if you read a spaced aerial and he's coming down or short hopping, like ace said
- down throw can usually be regrabbed at 0,not sure if it's guaranteed or how long it goes for, but no more than 10-15%
- down throw to double hit nair also is a thing at really low percents. Again, not sure how guaranteed (haven't been trying this lately, usually go for a regrab instead)
- tipman and eikeldrop wreck him
- you can punish a shielded fsmash with wd oos grab or fair oos, not sure about a tipper, getting a ps helps for sure
IMO Marth is a pretty doable matchup. Still in marth's favor, but one of the easier top tiers.
The most troublesome things he can do IMO are techchase with throws, juggle you in the air with his huge hit boxes, and abuse dtilt(what are you suppose to do when a Marth is spamming dtilt on your shield in the corner? They always fsmash if I jump
)
Edit: won my weekly today, but there was only 9 people for some reason, and most of the good people didn't come, so kind of a hollow victory. Didn't lose a match, it's fun wrecking with Ganon in bracket for once lol. Went all Ganon except Falcon for a few fd counterpicks, and Marth against peach on fod when I couldn't ban it for ****s and giggles. Is Marth a peach counter? I'm clueless but it was working pretty well