So.. Marth...
play him at the ledge ala M2K in Melee against Fox on FD. Rolling through him is too much risk in this scenario, and in every other stage position, rolling into him is too free of a positional advantage/free punish a lot of the time for Marth to deal with.
Shieldbreaker is likely our only "game changing" move. I've started to get comfortable with charging it long enough to get to the second stage of the charge, which is sufficient to break every shield I find (it does like 13%? damage). How people start to respect shieldbreaker as you camp in and around the ledge gets results.
But yeah, Marth is pretty awful in this game. He could be mid tier. But now horizontal and fall speeds have come out I'm just like "yeah..........................................."
I'm fighting through it, but it's the truth, he may not be viable. Sheik's fair is better than our entire moveset practically, and that match up isn't going anywhere but down, it's the MK match up in Brawl without the grab combos and MK now has a transcended priority fast/comboable long range projectile, JOY. Diddy is fine, until they camp you hard enough because Marth has very little to force pressure against a character who only needs to shield, roll and dash grab for stocks.
His rolls, dodges and shield are game-implied options Marth needs to be able to win against "projectile characters" (i.e. everyone, projectiles or not because he has no approach and his attacks are huge commitments, even down tilt), but his dash to shield is the worse in the game, his spot dodge is in the worst caste of the game, an average or below average roll. His dash grab is mildly good, but nothing to write home about.
Marth's moveset requires specific scenarios to be able to succeed (cause opponents to respect your moveset), but all of his character specifics are AVERAGE except for walking... which seems to take a lot longer to reach maximum speed and has much harsher turn around mechanics. His attack speed is waaaaaaaaaaaaaaaaaay overnerfed (as I start to compare to Mario, Diddy, Sheik, etc; it feels like Sakurai/Namco didn't want Marth being anything other than a counter and shieldbreaker spammer for wifi kids), and the lack of auto cancels on top of this means he just... doesn't have any moves he can use to beat good characters other than punishing whiffs with roll/dodge baits... Every aerial we use is a free dash grab or dash attack; at the very least close to 65:35 scenario in the opponent's favour. So we cannot afford to swing our sword or jump ever... just roll, hold shield and spot dodge and hope for whiffs...
So yeah, right now, I'm playing Marth with a rolldodge spam-like game, because none of his moves actually challenge good characters directly, he loses out to them all unfortunately... It's quite daunting. Thank **** for tipper forward smash or shield breaker... without these two moves having such HUGE rewards, this character would be one of the most nerfed in Smash history tbqh, Captain Falcon/Jigglypuff from melee to brawl level treatment (so not 64 to melee kirby treatment).