Woodruff is a ranger for the Forest and Wildlife Bureau, who works in an area close to Violet City. He told Ash that he was free to catch as many Heracross as he wanted, but warned that he might unintentionally disturb the balance of nature. Woodruff described a case of commensalism in which the Heracross' strong teeth made the tree sap available to the Butterfree to feed on. Misty noted that the forest was in a terrible condition, which Woodruff explained was the effect of the invading Pinsir that go unchallenged by the peaceful Heracross.
Woodruff guided Ash and his friends to the area of the forest where the Pinsir lived, suspecting something may have been amiss with the Pinsir and their usual territory. All signs, including a destroyed rope bridge and a Pinsir mecha, pointed to human intervention, and he soon spotted the culprits, Team Rocket. He assisted the group and Heracross in defeating Team Rocket, and the Pinsir immediately returned to their side of the forest.