The gang of 12 are on their way to Vermilion City, but Melanie sees something nearby and Ash asks her the riddle: "You know what happens when you cross between an Oddish and a Gloom? you get an Oddoom." Melanie is eager to capture it and put Oddoom's database in the Poké Dex. Meanwhile, Team Rocket is set on out to capture Oddoom with Cassidy and Butch by their side.