edit:
IB/Tai
do y'all have any critique on my marth? you guys played it and saw it the most out of everyone the whole weekend(of APEX that is).
I watched you play quite a bit sunday despite only playing you for one marth ditto.
You need to be more aggressive, particularly with dtilt > iasa frames. Also use a lot more upthrow.
when you attack air to ground and your opponent ruins your spacing with walk/run in shield or WD or something you can do more l cancel into dash or sidestep. I'd start with aerial > dash against fox sheik falcon because they can grab your landing lag the easiest and fox in particular doesn't care about spot dodges cause he can shine you out of it on a whiffed grab and that leads to a grab anyway. don't land on the ground in a nair vs fox ever. just don't do it. don't even use nair against sheik at all. against slower characters that screw up your landing spacing try l canceling directly into a spot dodge and work from there.
with your aggression, spend more time trying to work your opponent into a bad situation. marth can basically dial-a-combo at any moment but if you combo them to 80 and hit them up high you haven't really helped your position. rather, use his sword and try to carry them to the edge of the stage where you can leverage a positional advantage so your range has more value. once your marth can dominate an invisible yet understood portion of the stage, he becomes much more threatening. if you were watching me play tai with zelda for example, most of the advantage i got against him with zelda was because the about half of the things he was doing weren't threatening.
just because you're swinging your sword at your opponent doesn't make you a threat. it's not like fox where feet = victory and shield pressure = hitting their shield, and you probably see the game at least mostly through a fox-tinted lens from playing him so long. instead you want to actively screw people by making them unable to make it back to the stage because there's a marth in the way and his dair apparently hits everywhere. marth's pressure game comes from his ability to eliminate options based on character position and pinning/trapping them into hopeless positions. it's most obvious with things like marth vs fox on FD but you can replicate that play style for most "regular" match-ups (basically neutral stages and not against jigglypuff) and that's how you want to play.
a lot of newer marths like to use dash attack. it's not that good. use it sparingly at best.
once you start building more natural defenses into your gameplay and make your marth more threatening you can get away with much more aggression and you'll close out kills much faster. marth is a stupid, stupid dangerous character when played correctly but he's a mid-high tier at best when you don't know what you're doing and misplaying him in any way. using upthrow more than your other throws will help your ability to trap/kill opponents by a LOT because basically being above marth is a horrible position in a very general way and upthrow is the best way to make it happen. the more you up throw > obvious combo, the harder of a positional advantage you'll be able to leverage over and over again which leads to free wins. also feel free to use the tried and true tactic of "grab them when they land" which is abusable not only by marth, but basically any character with a legit grab in all 3 smash games.
not all of this stuff applies to you directly but it's all in some way applicable to the idea that you should be more aggressive. like you don't use dash attack much from what i can tell but i'm trying to convey the idea in a thorough manner so you'll get a feel for what i'm talking about.
also don't kill yourself twice per match like a ******/me.