Other options: Hi Jump Kick (breed with Hitmonlee), Cross Chop (breed with Machop), Shadow Claw (TM65), Shadow Ball (TM30), Rock Slide (TM80), Calm Mind (TM04), Hidden Power Ice (TM10), Vacuum Wave (breed with Hitmonchan), Choice Scarf (Battle Tower Prize), Life Orb (Battle Tower Prize)

Hi Jump Kick is less powerful and less accurate than Close Combat, but it won't lower your defenses. If you don't want to let Lucario's nice set of resistances go to waste, then feel free to use this move. Cross Chop has the same power plus the increased chance of getting a critical hit, but its accuracy makes it less viable than other Fighting moves that Lucario learns.

Shadow Claw can replace Crunch on any of the physical sets. It's slightly weaker than Crunch, but it also has a higher chance of inflicting a critical hit and isn't resisted by Fighting types. Likewise, Shadow Ball can go over Dark Pulse on the special set.

Rock Slide can go over Stone Edge if you prefer accuracy over power. Lucario is rather frail so having its attack miss in a crucial situation could lead to its defeat.

Lucario can use a special set with Calm Mind, but the process of setting this up takes too long. In the end, the Choice Specs set is more effective since you can hit hard and fast with a boosted Special Attack right off the bat.

Hidden Power Ice is an option over Dragon Pulse on the Choice Specs set. It will do a lot more damage to Dragons with 4x Ice weaknesses like Salamence or Garchomp and is supereffective against Flying types as well. Vacuum Wave is another good option on that Specs set, being a special version of Bullet Punch.

For items, you can use Choice Scarf instead of Choice Band or Specs. It gives a welcome boost to Lucario's less than stellar Speed and lets it surprise enemies that are normally faster than it. Life Orb can be used in place of Choice Specs if you prefer versatility, but Choice Specs offers more power which is more important in the long run.

How to counter Lucario:

Lucario is a very diverse fighter and the first step to countering it is to find out what kind of a set it's using. Most Lucarios tend to use physical attacks, so we'll go over counters to those sets first.

Flying types are generally good counters to Lucario. Gliscor easily switches into any of the physical sets with its excellent Defense and resistance to Fighting. It packs a STABed Earthquake that can defeat Lucario with no problem. Salamence and Gyarados can Intimidate Lucario and usually know a supereffective move like Earthquake or Flamethrower. The only thing they have to worry about is getting hit with a Stone Edge.

Weezing takes little damage from any of Lucario's physical moves and can give it a nasty Burn using
Will-o-wisp.

Dusknoir and Spiritomb with Shadow Sneak have no problem against the Reversaler. They are immune to Reversal and if Lucario tries to attack with Crunch, they will hit first with Shadow Sneak.

Hippowdon can easily take two Choice Banded Close Combats, heal the damage with Slack Off, and strike back with Earthquake. It can take a Swords Danced Close Combat too, but only if Lucario is not holding Life Orb.

The Choice Specs set is much harder to counter mainly because many special walls in the game are weak to Fighting. Still Spiritomb saves the day again by having no weaknesses and an immunity to both Aura Sphere and Psychic. Cresselia also does a fine job of walling it. Even without any Special Defense EVs, it can easily survive two Dark Pulses
Heracross can serve as a counter if you're careful not to send it in on a Psychic. It has above average Special Defense and resistance to Aura Sphere and Dark Pulse, Lucario's two most commonly used attacks.