How do I catch that stupid Leprechaun? Do I need something special?

Ignore the little jerk. He's impossibleto catch. Later in the game you will end up on his Island, and without a fight he will say, "You have caught me, all my treasure is yours," and zip off witout a struggle.

Actually, I hacked him to little bits and got the most EXP in the game up to that point, long before I was told to catch him. You still get his treasure later regardless.