Believe it or not, Lucas can approach. He's probably got better options, too. Now I don't main Lucas, but I've used him to win certain matches I had a hard time doing with Ness, which is strange how that ended up working, but I was usually the one who made the approach. I've even done this against a Ness main. Lucas can come at Ness with nair, fair, possibly dair and PK Fire. At any rate, I can see this being 50:50 as this is fairly similar to ditto matches. Both characters have a slight unique playstyle, but they're not too far from different.
Both characters have their own move sets in a way, but both also have almost the same projectile. Ness' PK Thunder is equivalent to Lucas' PK Fire while Lucas' PK Thunder is equivalent to Ness' PK Fire, if you can understand where I'm going with this. Exploiting what the characters can do with methods like B-sticking do however make them pretty different, though, though this was probably not meant to be. Anyway, despite what you believe on approaching, I'm sure Lucas can make the first move if he wanted to.