Dude, Lucario is the only Pokemon with a real backstory other than Mewtwo. Its backstory was shown in Lucario and the Mystery of Mew (that's right, it has a movie), but I'll sum it up for you: Lucario was a Pokemon that served Sir Aaron. In the midst of a violent war, Aaron betrayed Lucario by trapping it in a special staff. Several centuries later, Ash and crew accidentally freed Lucario. Lucario spent the entire movie trying to find out why Aaron betrayed him (she...it...whatever). Granted, it's not as deep as Mewtwo's but it's pretty darn close.
Now do you see?
Oh, and, you're right...I AM a genius, thanks for noticing