Lucario

What was once a dex-filler fan-favorite is now the king non-shadow Fighting Type thanks to the stellar Fighting Type move, Aura Sphere. In terms of DPS, no other non-shadow, non-mega Fighting Type can touch Lucario's performance. And speaking of megas, Mega Lucario is here!

Best PvE Offensive Moveset

• Aura Sphere is Lucario's best charge moves by far, and should be paired with Force Palm*. Counter works as a slightly weaker alternative if you don't have access to Force Palm.

• Bullet Punch and Flash Cannon can work for a Steel moveset

• Close Combat, Shadow Ball, Blaze Kick, Thunder Punch and Power-Up Punch aren't worth using offensively.

Best PvE Defensive Moveset

• Counter offers more damage and wider coverage, outclassing Bullet Punch and Force Palm* in most scenarios.

• Blaze Kick offers good neutral coverage and it comes out fast and quickly, making it the defensive Charged Move of choice.

• Thunder Punch is competitive with Blaze Kick, though it is easier to dodge.

• Shadow Ball has outstanding neutral coverage and power that pairs amazingly well with Counter, but is easy to dodge.

• Aura Sphere and Power-Up Punch are great, but leave Lucario with a mono-type set unless paired with Bullet Punch that can be easy to counter.

• Close Combat is bad on defense, while Flash Cannon is also bad but at least pairs better with Counter.

Force Palm and Counter have similar parameters; both are excellent moves and provide Lucario with reliable Fighting-type damage and decent energy generation. Bullet Punch is okay, but pales in comparison.

Power-Up Punch can be used to bait shields and apply an ATK buff, but its poor damage means it rarely punishes opponents for not shielding. Close Combat has been more popular due to its significant damage potential, despite its significant self-debuff. It is recommended to charge enough energy to use two Close Combats in a row, rather than using it immediately when available. Shadow Ball is preferred for its mostly neutral coverage, but it's also valuable against most Pokemon that would resist Fighting-type damage. Blaze Kick hits a number of types for Super Effective damage and has a low energy cost, making it a worthwhile option. However, Fire has some coverage overlap with Fighting, making it a bit less valuable than it appears on the surface. Thunder Punch can hit some Flying- and Water-type Pokemon for super effective damage.

Shadow Ball itself isn't necessarily mandatory if the metagame lacks good Ghost- and Psychic-type targets. Lucario can utilize two of its other Charged Attacks to better suit itself in said metagame.

What about Aura Sphere? 

Added with the Dec 11, 2019 move rebalance, Aura Sphere features identical stats as Shadow Ball, but instead is a Fighting-type move which has STAB. While this may seem quite powerful (and it is), the increased energy cost compared to Close Combat makes it more difficult to access. It is however quite good for Rocket battles if Lucario lives long enough to use it.