Oh my, you need to go to Slateport or Lilycove. Possibly Battle Frontier, but I believe you need to go to Slateport and someone there and then he'll say something like: "Oh, I buried this map when I was just a lad. But now you've found it, so I'll take you to Faraway Island. I don't remember its level, but it should know a move called Psycho Boost (si-co-boo-st); which is more powerful then Psychic. Also, at least in the Japanese version, Master Balls and Ultra Balls don't work against it. Also, the Poke Ball will make it so it's automatically captured. And with a Great Ball, it's even more rare, but harder to catch. I'm not sure about Luxury Balls, Timer Balls, etc.. Hope I helped!
Yes I'm a boy.
Hahaha! My evil army!
Um.. did I say evil? I didn't say anything..
Fine, I did, but.. I meant.. uhh.. good! Yeah, good!
Wanna change the subject? Party!
Or we can make music..
how 'bout rocking?
A game of ball?
Not what I meant.. You're not falling for this, are you? I'm a boy