I vouge as a ness main in PM that he has a great deal of tech due to a few of his aspects. I was like you I too was victum of using the god tier lucas, but I see ness as a more simple version of lucas.You could easily call lucas fox and ness Falco. Lucas has continuos, super fast multihitboxe moves that require either fast DJC's or super short hops and perfect L canceling and chases to mix up combos and probably a simple finish like a dunk or an up smash. Had ou already mained Luca I would assume that you know about his Pk Shine (his down B) and how its very similar to a shine since you can jump cancel it and start combos off of it Like a shine.
Ness on the other hand Is slower and has single hit box moves. He requires a tad bit more patience and timing, infact a little more mind gameplay due to this. Unlike lucas you cant pull off more than a 3 hit combo and still keep your opponent close enough for a kill move or a spike set up. Ness simply is catch your opponent off gaurd so you can kill them on stage with a back throw, back air, or a forward smash (tipper preffered). When it comes to combos, you may need to mix it up with alot of well timed dash attacks and Pk Fires, and as soon as the apponent is in the air, if they arent behind you set up a few forward airs to rack up damage. Ness has many moves to keep your opponent from getting too close, so I would also advice a spacing game so you dont keep it an upclose and personal game. Ness isnto too squishy but if his moves require space, so short hopping into a nair, downtilt, jab, down smashing or up smashing is a good way to keep distance because those are his faser all around hit boxes that basically say "GET OFF" the move that probably triumphs all is his down B hi Pk shine. His down B is the closest to a shine you can get with out him being a spacie. The only problem is is that its just a frame or 2 slower than fox and falcos shine but its knock back and hit stun are worth it and if thats not enough, the hit box is continuos but after the first box it doesnt make your enemy flinch much so after you pkshine you want to jump cancel. Thats were most of his tech comes in is knowing when to shine. Ive experemented with it alot and ive learned that Nesses shine is unique cause it has a floating mommentum. For instance if you dashed at your enemy into a short hop Pk Shine you would float a short distance with your shine out at the same time still being able to create its rewarding knock back. My favorite tactic with this move is to B reversal it (which is the exact momment you put your input into oyour controller for a B mover (special) like the down be your tilt the control stick in the opposite direction to turn the move around) this will immediatley turn the mommentum you have with the shine around making you float the other direction AFTER hitting your opponent with the shine thus making it THAT much safer, after this you can mix up by jump cancelling into a back air, a PK fire, or wave land to secure saftey.
Thats my short crummy guide for ya
