Why is Lucario awesome?
Lucario is a really epic Pokemon. But he's awesome because he's awesome at a lot of things, which I hope to explain here:
Typing
Lucario is Fighting/Steel, so this gives him resistances to a LOT of things- Notably Normal, Grass, and Ghost, not to mention 6 others. He's also immune to poison-type attacks, which is really helpful. He gets all of this- for only being weak to Fighting (Which shouldn't even count), Ground, and Fire.
Stats
Lucario's stat totals are pretty high, so he can become quite powerful. He also has high Attack and Special attack, which help with the moves Aura Sphere and Close Combat. His high Speed will also help him get first strike on most enemies as well.
Aura
Again, Aura is great. Not only does it mean that in real life, he would be able to see through anyone or anything (I look at you, Zoroark), it also provides for the epic move, Aura Sphere. Not only does this move never miss, it also has 90 power, making it, combined with its Same Type Attack Bonus (STAB), gives it 135 power. To put this in perspective, Hyper Beam has 150 power. Aura Sphere also has 20 base PP, up to 32 (with a PP Max), so you can use it on everything!
Appearance
All I'm going to say here is that he looks badass. Just look at him!