Sweet jesus I just played a very good Marth named raytay. My Kirby went even with his Marth and it was nerve-racking, nail-biting, fighting-for-every-inch matches. I forgot how much you have to change up what you're doing when you play Marth.
If Marth is moving forward, he's going to keep moving forward through you and it's better to just air dodge through him, or wait 'til he commits to a FAir before SHBAir (from below), or FFBAir (from above).
If Marth doesn't have forward momentum, 'dance' above him with your jumps and bait a smash. If he dash>USmash, dodge into him and FF so while he's stuck in his lag you can punish. If he pivot grabs, wait for it and punish with BAir. If he jumps, you jump; and move away because it's best not to outright challenge Marth - instead you want to wait til he commits.
When Marth is dashing at you, you have a few options to choose from AND YOU NEED TO MIX THEM UP:
- Either run at him and roll past him. <---reset
- SHAirDodge at him and then FFDrift back to feint an aerial approach, or
- SHAirDodge through him and create space <---reset
- Jump! and jump up and over with BAir covering your ***. <--- reset
- Run in and shieldgrab <--- this option will scare Marth away from the front ground approach and push the battle in an aerial direction
- Shield <---If you roll past him afterwards and move to create space, depending on what attack he did, this might be ok. It also might be the worst decision ever. Double-edged sword, best avoided.
-Spotdodge <---Also a double edged sword for the same reasons above.
If you miss a grab, miss an attack, airdodge too close to Marth, land to close to Marth, or generally put yourself in a position where you think Marth will hit you, FTILT!!!! FTilt will save your *** in this MU.
A good bread and butter combo is RARBAir>FTilt, or simply BAir>FTilt.
Two things that will help you in this match-up without having to know anything else is that FTilt will cover your *** on the ground level, and UTilt will save you when he's over you.
FAir, AerialHammer, USmash and Rock are NOT to be used in this match-up, with the exception of using FAir rarely as a mix-up instead of BAir when Marth approachs, and you are already in a mix-up of meeting Marth aggressively in the air (which you shouldn't do 'less you're above him and even then it's risky).
I haven't really said anything about UAir, but it's useful when he's a double-jump length above you and you can read him before committing to UAir. Alternative if Marth is less than a double jumps length away from you, you could use UAir as a mix-up (a mix-up for when you do NOT challenging his descent upon you, which is what you should do because you could instead read him and either a) spotdodge>UTilt b) pivot grab on his DAir or c) run like hell and reset <--best option).
Lastly, and probably most importantly, CHANGE YOUR RECOVERY FROM OFFSTAGE. If Marth is waiting patiently on-stage, DON'T LAND ON STAGE. Don't even bother trying to go over him. Simply put, he's too fast. Just grab the ledge. Then comes the hard part:
- Press forward to do a simple get-up. <---You just started another layer of yomi where you have to get away from the edge, or create distance between you and Marth by going through, over, or around him. <--my favorite because I love yomi layers and am pretty good at it, giving you the options to: roll, shield, airdodge through, FTilt, FSmash, jump away from, jumps up, jump towards. <---gives you the most control.
-Roll get-up <---same as above but isn't as good because being in the roll is dangerous.
-Fall away from the stage <----reset
-Fall down and UpB <--- reset with the possibility of hitting Marth, which would create a window to get off the ledge but requires DIing the UpB and reading Marth's edgegaurd attempt.
-Utilize jumps <--- puts you in a very dangerous position because you're, not intentionally but nonetheless, aggressively approaching Marth <--- probably the riskiest option.
You generally want to recover high because being at or below stage level means you're at a disadvantage.
If Marth comes out to meet you, simply use your jumps intelligently to avoid the attack and get back on stage. Once you've avoided the attack, create distance.
If Marth comes out with SHFAir and DOESN'T HAVE FORWARD MOMENTUM AFTERWARDS, he's still dangerous because he still has the option to touch back on the ground and U/D/FSmash or D/FAir.
Tl;dr- Create Distance. Don't Challenge. Mix it up A LOT. Feint often and avoid even more often.