My apologies, just edited it. So what are Lucario's weaknesses?
Exploitable recovery. I main Falcon, and I have perfectly calculated when to dair Lucario in the middle of a straight line recovery. Of course, they don't have to recover from a straight line, but that would 90% of the times to them landing on stage. If you see them doing that very often, punish with your most powerful move. When tilted bad, that recovery has insane amount of lag.
His air hitboxes are somehow bad, as they aren't very big. But be careful with that bair, it kills stupidly low in a situation of 100% Lucario against a 75% you (mid weight).
I was also salty to Lucario
because I found kind of unfair and salt-provoking that Aura mechanic. You are beating the hell out of him, but then he up throws you and double uair and still deal like 35 if not 45% with a good read. Also, when you think you got him, he punish you like REALLY hard.
THEN I learned that Lucario might be all that salt-inducing, but you need to control the salt and the anger. Playing salty/angry won't make you play better. Against a Lucario, you need to control the flow of battle. Don't let Lucario do it.
You might need to change your usual playstyle, and play really (like really) patiently and calm, and watch the battle calmly.
PS: I play Falcon a lot, and he makes me come to him while he charges AS. I perfect shield it and quickly dash grab/dash attack, but he spot dodges and punish me with those already mentioned 45% dmg combo throws. If this ever happen to you, remember to relax, and learn how he punish before he gets the aura. If he spot dodges, pivot smashes will do the trick.
Hope I helped.
TL;DR: Play really patient and observe his habits. Punish hard and kill early. Having any kind of easy meteor will help.