I disagree with the aggressive playstyle response to Ness and Lucas. So many of their attacks have a better priority then yours, and their aerials are dangerous to get caught in. This is one particular matchup that I really don't like playing...it's pretty hard for me too, and I'm not always successful either.
I'd say that needle camping is huge in this matchup, so use it properly, but don't over do it, becasue their aerial maneuverability will make it hard for you to always be able to use it. More then anything else...play tactically sound. Shield grab shield grab shield grab, ESPECIALLY agaisnt Ness who is going to be using BAir and FAir like crazy. Important to remember however, is don't try to follow up a throw with a direct attack...most of the time it's just going to end up getting you messed up by some aerial. Wait for them to do something, or feint an attack and then capitalize.
This is one of those matchups that just requires you to be really smart and quick to punish. Overall, I would just avoid being in the air vs. Ness in general, I find that it's a bad position to be in. Keep it on the ground when possible and play intelligently.