you can use the platforms to avoid the lasers and try to snipe him with shai drop / runoff aerials. that only works if falcos don't want to be patient, though. you can also try powershielding the lasers, which is hard, but it's the best answer to them. remove the spring from your controller, boot up 20xx, do whatever, and practice that. i'm not consistent with it now but i wish I was. you can also just take the lasers and do whatever before falco does what he really wants to do to you. the lasers don't stun you for that long, they're just annoying, especially if they catch pressing lots of buttons. 20xx is useful for this too; get shot, get shot a lot.
about powershielding: remember that you still get shield damage when ou do it. i haven't tested this, but i would imagine that it would become harder for pichu to powershield after 3 or so lasers. it's still possible, and i've done it, but i think it's something to keep in mind.
ideally you don't want to let falco feel comfortable enough to approach you. if it's a smart falco that has reasonably good tech skill, falco can rip pichu apart from just one solid hit. if you know what falco vs fox is like, pichu wants to play a lot like fox with the sort of passive aggressiveness of not approaching much but finding obscure openings and punishing the hell out of falco for them.