Up Smash can be used as an edge guarding tool

[nessokman]

I was trying it in bot games against Mario just to check. When Ness is charging his up smash, his Yo-Yo will actually hang off the ledge. If you place yourself just right, you can catch people as they try to recover. It will hit them over and over with a small amount of damage. During the time they are being juggled by the up smash, you can release it and they will take a full power Up-Smash.

In terms of consistency, I've gotten it to work a fair bit. It requires pretty perfect spacing from the ledge to get right. With this, PK, Thunder, and PK Flash, Ness has some serious edge guarding potential.

 

[EGsmash]

Down smash works this way too, and actually works a bit better than up smash, especially if you get good at running up to the ledge, reversing and throwing out your smash attack.

With DSmash, once your opponent starts getting hit from the charged yo-yo you can release the attack which activates the multi hit and horizontal knockback away from the stage, and it's both a great gimp and a kill move. USmash is good too and is now a kill move, but iir tends to send opponents upward, making it less of an edgeguard at lower %. Characters with vertical recoveries who don't have huge hitboxes get absolutely murdered by a charged DSmash off the ledge - think Falcon, Ganondorf, Samus, ROB, Megaman, and even Link sometimes. I've even cheezed K Rool with it, although it's easy to get hit by his rotor and there are better ways to gimp his recovery as Ness.

BTW, PK Thunder's tail ends Wolf's stock offstage 100% of the time.