The leprechaun wins easily. His one weakness - the unsatiable desire to clean dirty shoes - couldn’t be overcome by Chuckie. Certainly, the tiny doll has dirty shoes, but they’re miniscule, and would take but a few seconds to clean. Plus, they probably can’t be removed, which would prevent Chuckie from distracting the leprechaun by throwing them off to the side while he runs away, or grabs a hatchet to bury into his skull.