haha don't worry, i know this with MK, because I analysed already this MU. But I'd never a good Peach as oppenent until my last tournament.
Against MK, you can't allow to wait until he makes an attack, you must predict his next attack, so you can move in the right place to punish this attack.
Like MK's fair, you should wait until he makes the attack, but you should already jump and be ready to bair him near the end of the attack, same for his nado, which can be punish from the ground with Usmash, or like the end, with Fair/Bair/Dair. Or you can try to predict his nado, and approach him during the nado, let you touch from it, try to predict which way he'll escape, TDI you out in this direction, and you can punish with Dair (you normally TDI out so, you wil be in the air this moment)
etc... xD
Falco isn't that difficult. It's a taff MU, but be prepared with low %, that he will use laser to make you approach and not to make you %. He wants to CG you, so he can makes you 50-60 % with a nice read in the end. I think, you should approach in crawl and ps every laser, but don't stop, go ahead, and wait for his grab move, roll in the opposite direction of his (when he use normal grab, roll backward, when he tried to brg you, roll in his previous position, and then, he will go back on his campplay. Best stages against Falco, which I play well against him, are BF, where you can camp at the highest platform, or SV, where you approach and just need to shield and try to read his moves (ex: s-h double laser to bside)
Besides, against bside of falco, you should use nado, it works not bad at all
oh man, sry, I wrote so much...
Anyone can send in Vids, so feel free.
