Falco vs perfect powershielders:
mix up laser heights (high lasers don't get powershielded, but marth can dash under them), empty short hop (or even shoot fake lasers - japan is really big on this because of FD only), shoot a low laser then short hop over it when it gets powershielded, more dashdance(!!!), or powershield the lasers back at them.
I'm not a great powershielder myself, but according to diakonos, the best powershielder on the west coast of north america, stuff like running forward and shielding before you SHL or dashdancing before you powershield makes it much trickier to time the powershield.
but yeah, when people powershield lasers they aren't actually reacting to the laser flying through the air, they're reacting to the telegraphed movement of the Falco. there are a LOT of ways to deal with perfect powershielders...
...and my personal favorite is to go back to Fox >_>