Old Man Shuckle is a one-off character from the episode "A Better Pill to Swallow." He's a Shuckle juice maker who's basically built his whole operation around harvesting juice from wild Shuckle in his area and turning it into medicines. When Ash first meets him with an upset stomach, Old Man Shuckle's remedy does the trick.
He tries to recruit Brock by offering to teach him his secret recipes—all Brock has to do is catch him a Shiny Shuckle. Brock's actually tempted, but ultimately decides that relying on man-made products doesn't fit with his goals as a Pokémon Breeder, so he passes.
The character's got a funny side too. While Ash and Brock are genuinely impressed by the mysterious beams of light that burst forth whenever Old Man Shuckle talks himself up, Misty immediately spots the trick: he's just holding a flashlight behind his back.
Content compiled by AnimeList.moe from publicly available sources.
