Me again, long time no see. Missed ya'll, and now to my first post in a long time.
RED LEADER, GOING IN
-Work Up
-Bullet Punch
-Vacuum Wave
-Extreme Speed/Anti-Psychic
Item Attached: Focus Sash/Lum Berry/Life Orb
Ability: Inner Focus/Justified
EVs and Nature:
252 Atk / 252 SpAtk / 4 Speed
Hasty/Naive Nature
How many Pokemon can run a moveset consisting of a boosting move & 3 priority moves? How many of them have the raw stats to even consider such a gimmick? How many of them can run physical and special? MegaLucario could've pulled this off better, but the game is what the game is. Work Up is your boosting move, +1 to Atk & SpAtk will leave your opponent guessing as to how best to counter. Bullet Punch and Vacuum Wave are STAB and get priority. No worrying about speed tiers with them. Extreme Speed is also priority, and hits stuff that would feel safe taking Steel and Fighting attacks. Anti-Psychic means "counter Psychic Terrain." Shadow Ball/Claw or Crunch/Dark Pulse are my recommendations, but Lucario's got plenty of coverage options to choose from.
Focus Sash is preferred to guarantee two rounds of action (Take hit, live at 1HP, Boost, then hit before they take you down) out of Lucario. Lum Berry can be used if you find yourself getting countered by status instead of direct attacks more often. Life Orb is for more damage. If Lucario's going to be your Dynamax, try Weakness Policy. Abilities...Adaptability would be ideal, but since there's no MegaEvolution in Galar, anything except for Steadfast can work here. You're relying on priority to negate Speed altogether, but a Speed-boosting Nature is still recommended to patch your Speed; Lucario's gonna be 1-shot by anything Super Effective and moderately strong anyways, so pick your poison.
PROS:
~Unexpected. The Meta is pretty stale, with any experienced trainer knowing your entire strategy upon seeing the Team Preview. No one expects gimmicks, and as far as gimmicks go, this one is probably the best.
~Immune to Poison, Paralysis doesn't hurt as much because your attacks go first all the time, and Burn does not completely shut you down (if you run Shadow Ball or Dark Pulse as your Anti-Psychic, you can laugh at Burn).
~Togekiss can't flinch you to death.
~Nobody likes a boosted priority attack to the face.
~Completely ignore the Speed tier altogether.
~Late game cleaner, has potential for a reverse sweep.
~No accuracy gambles.
CONS:
~Shut down completely by Tapu Lele (when it comes back) and Tsareena unless you replace Extreme Speed with a coverage move just for them.
~Assassin, not brawler; bring it out too early, and you've got an expensive Sash-breaker. If you don't save this set for late game, when all your checks/counters are weakened & status'd, then you've wasted a team slot.
~Again, this is more gimmick than viable because of the low BP of your STABs; no other Pokemon has any chance of pulling this off, though, but I won't deny there are stronger movesets you can use.
TEAMMATES:
~Clefable can switch in on the Fighting types that Lucario hates, and Lucario can handle the Steel types Clefable hates. Toxapex is Toxapex, and hard-counters the Fire types Lucario fears, while Lucario can finish off everything Toxapex weakens. Torture is illegal, but if the rest of your team are Excadrill counters...
~Gyarados can punch holes in Lucario's checks, and Lucario can finish off whatever survives Gyarados' wrath.
~Alolan!Ninetales and Grimmsnarl can provide Screens (Aurora Veil and Prankster-Dual Screens, respectively), and check Fighting types that would OHKO Lucario while Lucario handles Steel types that threaten them.
~Galarian!Rapidash, Gardevoir, and Hatterene provide offensive synergy to Lucario's Steel & Fighting STABs, can check Gengar (and other Ghost/Poison types that laugh at this moveset), and like Clefable have good defensive type synergy.
OTHER OPTIONS:
~Poison Jab. Easy to forget, but hard-counters Tsareena and checks Tapu Lele, both of whom shut down this set.
~Dragon Pulse. Nobody remembers that Lucario can learn this move; strong, reliable, and the only Pokemon immune to it are weak to Lucario's Steel STAB.