Professor Elm is a Pokémon researcher who serves as the resident professor of New Bark Town in the Johto region. He is a former student of Professor Oak, and he established himself in Johto to conduct research into Pokémon breeding and evolution. He is credited with the discovery of Pokémon Eggs and is regarded as one of the world's most renowned researchers in his field. He has also stated that he studies unusual Pokémon abilities, and he serves as the head of the Pokémon Preservation Council, an organization dedicated to surveying and protecting wild Pokémon. In the anime, he is shown conducting surveys of the Whirl Islands, where he captured a Corsola that later impressed Misty with its swimming and battling skills.

In appearance, Professor Elm is a middle-aged man with short brown hair and gray eyes, and he wears glasses along with a white lab coat over a collared teal shirt. His most defining trait is his intense absorption in his work. He has a habit of becoming so wrapped up in research that he becomes oblivious to his surroundings, sometimes forgetting to eat or failing to notice what is happening around him. This absent-mindedness is shown when he mistakes intruding Team Rocket members for Nurse Joy and nearly lets them take one of his Pokémon. He also tends to go off on tangents when discussing his research, and when he meets with his former mentor Professor Oak, he frequently argues over fine points of research. Despite these quirks, he is a kind and approachable person who makes friends easily and is genuinely devoted to supporting young trainers.

His role in the story is that of a mentor and starting point for new trainers in Johto. He is responsible for giving beginning trainers their first partner Pokémon, choosing from Chikorita, Cyndaquil, and Totodile, and he is shown entrusting these starters to several trainers throughout the series, including Casey, Vincent, and others. He also entrusts trainers with research tasks, such as delivering Pokémon Eggs or investigating unusual phenomena, and he takes a personal interest in the growth of the people he helps. His key relationships include his respectful but argumentative connection to Professor Oak, his friendly guidance of the Johto trainers, and his partnership with Pokémon such as Corsola, which he keeps in his lab.

Over the course of the anime, Professor Elm remains consistent as a dedicated and warm-hearted scientist rather than undergoing major personal change. His development appears mainly through his expanding conservation work, such as his involvement in the Whirl Islands, and his ongoing commitment to both research and the protection of Pokémon. His notable abilities lie not in battle but in scientific expertise: he is a leading authority on Pokémon breeding, Eggs, and evolution, and his discoveries have shaped how trainers understand Pokémon reproduction and growth. Through his combination of absent-minded brilliance, kindness, and scientific accomplishment, he stands as a central figure in the Johto region's Pokémon community.