Something I figured out with Lucas that carries over to Ness. If you are hanging on the ledge and quickly push away and then Up B, you can send your PK thunder onto the stage, hit it against the stage quickly and Ness will immediately grab the ledge again. It's pretty good for if you're being pressured at the ledge but with Ness you have a pretty small window of time to cancel your pk thunder so if you screw up you're dead. Try it out a few times. Pretty neat. When you do it right Ness looks like he teleports back to the ledge to grab it. Timing is similar to Falco's edgestall in melee.