i think you should....
try to stay like, (marth's) dash attack range away from falco. if you're too close, he can distort and mess with your sword spacing by running and jumping around. if you're too far.... well, he has the advantage because he has lasers (and you have a sword) and the entire stage space to move around and disguise his approach.
if he just keeps lasering, powershield or just try to get in carefully (or recklessly) with waveshield, dash attack, and whatever else you think will work against falco's lasers. if you want to try to play around the lasers rather than just powershielding them,
make sure to pay attention to
how he wants to laser (assuming he's lasering), also. like... if he's retreating or standing in place, get in that ***. if he's approaching with the lasers.... hit him and make him stop that.... and then get in that ***.
if he gives up on lasers and throws out a normally spaced (i.e. he doesn't overshoot it to call your retreat) nair, dair, or dash attack or something... well..... that's the moment you've been waiting for. grab him and make me proud
and if he's being a terrible human being and using empty SHs and fancy movement to bait your defense (DD grabs, ground moves), well.... then this falco's pretty good. try not to fall for the bait too much, and just make him pay when you can.