Lucario is effectively a different character in PM than in Brawl. Its signature aura system, rather than increasing its damage output at high percentages and low stocks, now allows players to fill a "super meter" that they can drain to unleash more powerful attacks and abilities, similarly to traditional fighting games. In addition, it now possesses a combo system, and many of its attacks, such as its forward tilt and up smash, have been redesigned to resemble attacks from more traditional fighting games.
Lucario has command of a type of interruptibility in the form of two "magic series": "neutral attack/dash → tilt → smash → special" and "aerial → special". If Lucario lands an attack on a foe or a shield, it can immediately cancel any endlag into any move farther forward on the respective list, allowing Lucario to string together up to 4 attacks extremely quickly.
Every attack landed by Lucario gives it "aura points", equal to 1.0x the damage dealt. Upon accumulating 50 aura points in one stock, Lucario earns an "aura charge" that it can spend to amplify the power of a special move by pressing the special attack and neutral attack buttons simultaneously. Lucario can hold 2 charges or 100 aura points and retains them between stocks. With these two mechanics mind, Lucario's strategy is to string together long combos to rack up damage and finish the opponent with an aura-powered special move. Lucario can also gain aura points by hitting objects such as balloons on Smashville or Shy Guys on Yoshi's Island equal to 1.0x the damage of the attack.
Changes from Brawl to PM
Lucario has a revamped aura mechanic that allows it to strengthen its special moves rather than increasing its power the more it is hurt. In addition, Lucario's fighting style is more combo oriented.
Up to date as of version 3.6.
In competitive play
Lucario has more variety with its palettes, which stand out more in team battles.
3.5 included a costume with a Gi that has the Fighting and Steel type emblems from the TCG on the back, an Expert Belt, and a Focus Band. This costume also has a black variation with a Choice Band and the Cobble Badge replacing the type emblems on the back.