Where can i find Lucario?? and is he easy to catch?

Answer 1

you can never catch a lucario, because they do not exist in the wild

HOWEVER!

you do get an egg on iron mountain. that egg will hatch into a riolu (7/8 chance it will be male)

you can evolve it into a lucario by way of happiness, but it will only evolve into a lucario (on a level-up) during the daytime

Answer 2

maybe he is only on the movies