I lol'd at "jib jab grab", you get a like just for that. If the rest of my post comes across as harsh I want you to know that these are the only issues I had with your video, the rest of it was very good and I agree with everything not mentioned below.
You say Usmash and Dsmash are underwhelming but Usmash is a good coverage move when you have your opponent on the ledge and it can be used to catch landings much easier than a grab or dash attack. Both moves can be used to catch people hanging on to or trying to sweetspot the ledge.
PK Fire is not quite as good as you make it sound simply because it's so easy to punish, given that this is a guide for newer Ness players we don't really want to encourage them to use it any more than they already do. Since you mention this (and magnet) can be used for edgeguarding you could have stressed the fact that your ideal edge guarding options are fair, bair, nair and PKT. Props for including the PKF DJ Cancel though.
His down special's name is actually PSI magnet, glad you included the magnet cancel tech.
PK Flash: don't encourage it. PKT is almost always a better option. Fthrow into PK Flash? This is a bad idea against any semi-competent opponent.
Throws: Uthrow is situational but very useful to start juggles. I try to use it when I'm facing center stage and my opponent is out of dthrow combo % but isn't at bthrow kill %. Fthrow doesn't accomplish much in this situation, while uthrow gives you a significant positional advantage without staling any of your important throws (also... fthrow/dthrow should both be staled slightly at this point so the lower damage is a moot point) and sets you up for uair/PKT juggles. Underrated move.
Tad unrelated to the guide but at the very beginning during the montage of clips you roll a lot, and that PK Fire was not at all safe. Mid level opponents will be able to punish you for both of those things.
Sorry for nit picking, I hope you view this as constructive criticism and use it to improve your own Ness game. Props to you for making this video, it's our most thorough if not best video guide.