You have no idea how hard a Marth that knows how to abuse the matchup is. I don't really feel like rewriting this matchup, but I'll make it short, sweet, and to the point.
If possible, keep the amount of time on the edge minimal. ECE's are great, but your ability to get off the edge is limited, especially after 100%. You will be punished. In this MU, you need to keep MK out of your space. You can do just fine against MK if you keep mid to long range at all times. Use pivot grabs to keep him from the ground. Mix this up with SH bairs.
If he is in the air over a roll's length away, use eggs to punish. Glide attack is nothing to worry about. If he is close to the roll's length bubble, then if he uses glide attack to clink with the egg, then pivot grab. Outside of that bubble, another egg ETS'ed backwards will be fine. If he is inside, you shouldn't be throwing an egg because it's too close and he can punish, so either pivot grab, usmash (which will probably clink), and fsmash (if he is flying in low).
A big problem that Yoshi's have is the don't know how to punish dair camping right above their head. You try to usmash, but they just jump slightly out of range. Eggs won't work since they can dodge and punish. Wait for a few dairs and just SH uair. Works pretty well. Also, wait for the 5th jump, read the DI and punish with grab. They will probably try to tornado on the way down so you should be fine.
Know all the moves that beat all of MK's moves. It's safe to assume that usmash beats almost everything. Same with fsmash. Even dsmash beats tornado lol.
The main thing to worry about is just making a wall that MK can't approach. This will take alot of mixing up with pivot grabs, bairs, egglays, tilts, and even weak thrown eggs. If you become predictable, he will easily get through and you'll take quite a bit of damage. This setup works extremely well against aggressive MK's.
Against passive MK's that just wait, this is where it gets really difficult and why I think 65:35 might be reasonable. An MK that just stands still or slowly advances, you don't have many options. You can throw eggs, but if he powershields and walks closer, if he closes in the gap, you will get punished eventually. You can try to dash grab, but spotdodge will **** you. You don't have much of a choice other than to slowly retreat his upcoming advance. Eventually, you will reach the ledge and be forced to jump over him. And you already know that you are in a bad spot when you are above MK.
You can beat this strategy, but it will take alot of effort. I'm currently trying mixups between bair and egglay. Bair easily beats spotdodge. Egglay beats some attacks and shield. Just as a note, this mixup is extremely powerful against all characters. Approaching the same way, back facing to the opponent, and choosing either move from this is an excellent option.
Also, against an MK that knows how to use tornado, it is extremely difficult to punish. You can if you predict it, but based solely on reactions, it is near impossible to catch an usmash or grab.
There is my crappy summary. Discuss
Agreed. If you get the grab, I would suggest the following, in order of deliciousness:
