One of the most threatening sweepers in DPP OU, Lucario has returned to the BW OU battlefield with some new toys. BW increased ExtremeSpeed's priority to +2, which means Mach Punch Infernape, among other such Pokemon, can no longer check it. In addition, the Dream World gave Lucario an ability it can actually make good use of: Justified. With this ability, Lucario gains an Attack boost upon getting hit by any Dark-type attack, which it can easily switch into thanks to its 4x resistance to Dark. Lucario also has a rare 4x resistance to Stealth Rock, which makes it difficult to wear it down with entry hazards. Its Steel typing brings it an immunity to Toxic; it therefore doesn't have to worry about poison damage prematurely ending its sweeps. However, there are many Pokemon capable of beating Lucario, such as Terrakion and Conkeldurr. Lucario also has four moveslot syndrome, which prevents it from covering every single relevant threat. Despite its flaws, however, Lucario is a deadly sweeper that will destroy any team not prepared for it.
Lucario's flagship set in DPP OU makes a return in BW2, and is arguably even better than it used to be, as ExtremeSpeed lets it take on Pokemon such as Thundurus-T, as well as Technician Breloom. As soon as Lucario sets up a Swords Dance boost, not many Pokemon will be able to take its attacks. Even Skarmory is almost always OHKOed by a +2 Close Combat after Stealth Rock, which is a testament to how powerful a boosted Lucario is. Although its base 90 Speed might seem like a letdown at first, Lucario gets ExtremeSpeed to circumvent that problem and allow it to take on Choice Scarf users such as Rotom-W, as well as priority users such as Breloom.
Lucario's fourth move should depend on what its team most needs covered. If Gliscor and Landorus-T threaten the team, Ice Punch is the preferred option; however, if you need Lucario to handle Jellicent, Reuniclus, and Slowbro, use Crunch instead. If none of these Pokemon concern you, Bullet Punch is a solid option that allows Lucario to get past Gengar, Terrakion, and Choice Scarf Tyranitar.Team Options & Additional Comments >>>
With good offensive stats and a good movepool, Lucario has quite a few more options. Stone Edge can be used on the Swords Dance set in order to hit Gyarados, while still hitting Pokemon such as Dragonite hard. As Lucario's Special Attack stat is actually higher than its Attack stat, a Nasty Plot set might seem appealing at first glance. However, too many faster Pokemon—including Alakazam and Starmie—resist Vacuum Wave, so it is not as effective as the Swords Dance set. An Agility set might seem appealing as it can beat typical revenge killers such as Terrakion and Choice Scarf Tyranitar, but it is very weak and Breloom can easily revenge kill it with Mach Punch. Calm Mind boosts Lucario's Special Defense while also raising its Special Attack, but Lucario's frailty makes this a pointless endeavor and Keldeo does Calm Mind better anyway.
Lucario can use Choice sets to decent effect, particularly Choice Specs. However, the likes of Latios, Scizor, and Terrakion do these better. Lucario can make use of an Air Balloon to set up on Pokemon such as Landorus-T Choice-locked into Earthquake, but it will miss the extra damage output from Life Orb, making its damage output noticeably lower against Pokemon such as Skarmory. Lucario has another ability, Steadfast, which boosts its Speed by one stage when it is flinched. However, because flinching moves are almost always paired up with paralysis, Steadfast is not a good choice.
Checks and Counters
Physically defensive Unaware Quagsire is one of the few physical walls that can take on Lucario and live to tell the tale. It cannot reliably switch in on Close Combat, but thanks to Unaware, it ignores Lucario's stat boosts, and can easily take Close Combat and retaliate with Earthquake. Hippowdon too can sponge +2 Close Combat and OHKO Lucario with Earthquake, but it will be severely weakened afterwards, and will fall to +3 Close Combat. Gliscor is capable of taking anything but Ice Punch, and can also OHKO Lucario with Earthquake; faster variants of Gliscor can check even Ice Punch Lucario. Sableye, although uncommon, can burn Lucario with Prankster Will-O-Wisp before Crunch does massive damage to it, which makes Lucario much easier to deal with.
There are other Pokemon that can check Lucario, depending on which moves it uses. In particular, Pokemon with Intimidate, such as Salamence, Landorus-T, and Gyarados, can come in on Lucario as it uses Swords Dance, take +1 ExtremeSpeed, and OHKO with the appropriate move. However, if Lucario carries Ice Punch, Salamence and Landorus-T must be careful of switching in. Jellicent and Slowbro can both comfortably wall and force out Lucario that lack Crunch, while Reuniclus can OHKO it with Focus Blast. Gengar can check Lucario that lack Bullet Punch and OHKO it with Focus Blast.
If all else fails, revenge killing Lucario is always an option. Celebi and Jirachi only need 176 Speed EVs to outspeed neutral-natured Lucario, and can both take a boosted ExtremeSpeed and OHKO Lucario with a super effective attack. Choice Scarf users such as Heatran, Terrakion, and Tyranitar also outspeed Lucario, and can take it on due to their resistance to ExtremeSpeed, though the latter two must look out for Bullet Punch.