This has actually been discussed a fair bit in
this thread here.
After a few more recent tournament outings (and the realization that I as a player have a horrific neutral), I've been having to re-evaluate how to move in neutral. Inevitably, I've come back to the convince your opponent to make mistakes method being the safer and more rewarding choice. If you've got your heart set on approaching someone who is at advantage, using movement options such as B-reverse/Wave Bounce ASC, BAS, DT, moonwalk, and the general movement tech to apply positional pressure is usually a better course of action.
Well, I don't usually play Lucario, but what I do is approach with a short-hop fair, followed by a jab combo, then side-b, but usually that's where it ends for me because I can't follow up with lucario to save my life.
If this is a 0% combo, you may find that a better option than FP here would be a tilt[probably dtilt]>usmash/ASC, since both options are pretty decent at positioning your opponent for an easier followup and punishing a possible CC (spacing dependent).