@bing: yeah that would work if you were fast enough but it wouldn't lower them to a point where they couldn't come back (esp fox). it would work well to bide time for a better edgeguard though. personally i just ftilt lol <_< i'll play around with what you said though next chance i get and see if it's effective or not
@wad: nairing spacies is hard to follow up for me especially at low%, which is why I don't usually go for nairs until they hit ~%20 (this is what I tell myself at least...-_-) unless I'm going for like super far crossup nairs so I know I won't get punished. if i do nair at low% i usually followup with uair, but theoretically it's probably better to see their reaction first.
nairing spacie shields means you should make sure the crossup puts you past their shine oos range. actually, nairing shields in general means you should crossup past the most far-reaching oos option they have until you're confident in reading their reaction.
also, controlling early/late nairs are really important if you want to tighten your pressure. nair on shield/character instead of instant nair out of jump for tighter pressure with stronger shieldstun and a smaller frame window for the opponent. early nair means you're covered in a hitbox for a longer duration of your jump, making you safer against certain offensive styles but also making you a hell of a lot easier to read if you keep doing it, not to mention the weaker, more lenient/predictable shieldstun makes punishing it a lot easier. weak nairs can be more effective at times in continuing combos than strong nair, and can establish a certain amount of control in the match because you're putting out a long-lasting hitbox that's flying everywhere (which effectively conditions your opponent as well).
vs pressure - all I can say is fox nairshines are vicious and should be outspaced at all times if possible, but usually getting caught doesn't mean death for pika. getting hit by shine is less of a worry than getting hit by nair, so if you know you're going to buckle to one of them at least make it the shine. falco pressure is more doable for me personally due to his low horizontal velocity and wider windows of escape.
oh yeah speaking of late nairs I want to experiment with super late nairs, like using nair after you almost fully crossup - if you look at the nair hitbox the 2nd frame the hitbox comes out is actually behind you so it'll still pressure while you're almost guaranteed to be out of their oos punish range by the time their stun ends (other than something stupid like falco sh oos reverse laser or w/e).
also every time i try to guess when an opponent is going to react out of shield i always try to catch with uair, but lately i realized im stupid and could be closing my margin of error with dsmash. harder to miss but easier to be punished for...ideas ideas...
so like i went on a huge tangent again, don't mind me >_< just wanted to write some thoughts lol
im super tired brothers
EDIT: holy crap woke up and saw this post this morning, i dont even remember writing half of this