I second Eye of the Tiger. IMO it just kind of fits with the Lucario additude. But its somewhat limited if you are going to try to match the beat to KO hits and stuff.
As far as lyrics go, anything to do with challenges, fighting, surviving, etc would fit will with Lucario.
Techno would be pretty good, but you need to synch the video to the beat otherwise it wont really fit together too well. My preference is for the beat to speed up right before a kill, and then slow down right after (for a few beats), then you can fit a couple repeat clips of the kill to the slower beat (not sure if that conveyed in words what I see in my mind too well).
Oh, and I think a metal version of the Pokemon theme without the lyrics would probably make a killer background song for a Lucario video. I tried to find one so I could post a link but to no avail.
I found a cool pokemon related song, I think its the RGB theme performed by a band. It sounds awesome. Too bad it has audience noise in it. Here is the link. Im still looking for more stuff too.
http://www.youtube.com/watch?v=4ugHc-8tprQ
And I have found it. The prize I was looking for. It was bound to come up if I scoured Youtube well enough. Its an electric guitar + base combo of the Pokemon theme song.
http://www.youtube.com/watch?v=VAkQJLWSDvU