Pokemon Badges 09/19/2009
A badge (Japanese: バッジ badge) is an item which denotes a Pokémon Trainer as having defeated a Gym Leader. Trainers need to collect a certain number of gym badges in order to qualify for a region's Pokémon League. Young Trainers usually begin their initial Pokémon journey by traveling from city to city in order to collect them. Badges are small enough to fit easily between one's thumb and index finger and can be pinned to a shirt or kept in a badge case.
In the games, Badges affect a Pokémon's behavior. A symbol of competence on the Trainer's part, badges force traded Pokémon under a certain level to obey. Additionally, Trainers cannot have a Pokémon use an HM move outside battle without the appropriate badge. Also, beginning in Generation IV, the number of badges a Trainer possesses affects the items that various Poké Marts will sell. The more badges, the more expensive and rare items become available for purchase.