The Battle Subway is a unique feature in the Pokémon video games, specifically introduced in Pokémon Black and Pokémon White. It allows players to engage in challenging battles against AI trainers in a subway setting. Players can choose to battle in single or double formats, testing their skills and strategies against various opponents. In the Battle Subway, players earn Battle Points (BP) by winning battles, which can be exchanged for valuable items and Pokémon. The experience gained helps players improve their battle techniques and team composition, making it a popular choice for competitive trainers looking to hone their skills.