KDJ vs random is not a good measure of Pichu's matchups.
These are my thoughts. Go forth and correct me.
I think it's probably easier than Sheik and Marth but not by much. Quite honestly I think it's Pichu's third worst matchup for a variety of reasons. I've seen it done a lot but not recently. And it was never two good people. Fox is (IMO) easier for Pichu.
I don't know numbers. I think it's really, really hard though. Possibly winnable at high level, but you'd have to be disproportionately better than the Falco to do it. I think it is impossible at top level, but that's M2K / Mango / Armada / Shiz territory.
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Laser is good against Pichu. If he's airborne it's free damage, if he's grounded you can approach or make him get away from the ledge if he's camping there.
Powershielding is not a great solution. Pichu can't really powershield to grab (or anything) because of his atrocious range. It additionally doesn't disrupt Falco very much because he can aim the lasers differently so he doesn't get hit by reflected lasers (see Lambchops).
Falco pressure is largely unpunishable by him so long as you stay spaced and in front of him. Don't go above him.
Pichu's moves don't ever win except Uair directly below him. Or Falco spaces terribly and Pichu gets WD back F-smash or something incredibly dumb.
Pichu can't grab Falco. And when he does, his combos will still not be as good as Falco's unless he's at the edge, FD (I don't know if Pichu can cg him but he can't get down from Uair so I guess that's okay), or perfect.
Falco is fat and can therefore crouch cancel Pichu Nairs to be not knocked over until about 70ish (possibly higher) and for a large portion of that range he can CC Shine (and other moves, depending on spacing and stuff). Pichu can space to go behind him and stuff, but that means you have to get closer to him when you start your Nair or not fast fall, which have other problems.
Fair --> move with Pichu does not work on crouch cancel (or in general). People don't know this for some reason and get away with it an assload, but it doesn't work.
Normally you can counter defensive crouch cancel spam by spacing a ranged move, a projectile, grabbing, or a mix. Pichu can't do the grab or ranged move and his projectile sucks, especially against Falco.
Pichu's horrible tech rolls also make for very easy KOs on Falco's behalf. Dair --> Dair and then tech chase with <insert move>. Pichu's tech in place has 24/26 frames of invincibility instead of the normal 20/26, which is good, but that's pretty moot because Falco's moves last for a long time, so there's a lot of room for error to hit him out of it.
To his credit, Pichu's Uair beats Falco's everything coming from below. If he can maximize his chances to abuse that, he can probably get some stocks. Having said that, I'm not sure how he'd go about doing it.
His recovery is also better.
