I played a pretty solid Lucario for the first time yesterday and after struggling somewhat the first two games I played him I realized a few things and started doing a lot better. Lucario's neutral game is garbage. Instead of rushing him down, bait him in with shdl until he's forced to approach. Once you get your hands on him you can drill -> waveshine -> uair/up smash the mess out of Lucario. Lucario's recovery is also pretty weird but what worked for me was to up-tilt near the ledge similar to covering Illusion recoveries in spacie match-ups. This seems to be pretty effective since Lucario has a really hard time sweet spotting the ledge. Depending on the %, up tilt can lead into an uair.
I basically decided to treat Lucario like a Falco with no lasers (Falco with a ****ty neutral game). He can combo you for free when you're at low percents but you also have a ton of near guaranteed combos on him.