I played a good amount of ness on the third day of Apex. He actually worked better than I expected against the players who haven't played online that much and aren't familiar with some of ness's tricks.
In terms of shieldbreaks, all the players I faced knew to basically not shield against ness. I was able to get Nintendude's Mario's shield to break in a semi-serious match but I messed up the punish (he was near the ledge and I uaired, naired, but then missed a spike, where I should have just done fair->dair) and there were a few other times I remember just missing the shieldbreak.
There are some things that I will definitely use to improve my game however, stuff like jab->grab worked very well (not the grab cancelled type of grab) and approaching with more fair caught some people off guard who were used to reverse horizontal bairs or dairs.
I played solely ness in teams which was all recorded. He's actually not that bad of a teammate as grab and dair are quick and useful. Plus if you have a teammate that can defend the ledge, he can stay off the stage and in the air for quite a while before coming back. With good ledge DI edguarding ness to death can take forever and leaves enough time for a teammate to step in. Hopefully the videos will be up soon.