Introduction
Lucario is your classic jack-of-all-trades character. His toolset is easy to use and reliable and it allows him to play the game in several different ways. Aura Sphere allows you to play the zoning game against most characters, Bone Rush is arguably the best whiff punisher in the game, Force Palm is a devastating CQC move dealing a ton of chip damage if blocked, and he has access to a powerful reversal in Extreme Speed. He excels at midrange, where he can poke his opponent and force them to play neutral while they can't reach him. His above average damage output allows him to be in the opponent's face as well and get rewarded for it. His frame data is also one of the best in the game, giving you the chance of using most of your tools while still being safe. And most importantly, he has a 150 CC Synergy Gauge, which lets him get his powerful Synergy Burst usually once every round if you don't make a lot of mistakes.
However, being such a versatile character isn't free. As a jack-of-all-trades, everything he can do, there's always a character that can do it better than him. His zoning is outclassed by characters like Chandelure or Gardevoir, his damage is outclassed by Machamp, Garchomp or Aegislash and his movement is bad when compared to characters like Decidueye or Weavile. His Field Phase is pretty lackluster, having problems to win if the opponent doesn't make any mistakes and his homing attack low priority makes it usually hard for him to use it. And even though his tools are reliable, they're also simple and linear. Good players will force you to be creative if you want to deal some damage with him.