The Pokémon Indigo League, also known as Pokémon: Indigo League, is the first season of the Pokémon anime series. However, it seems like you're looking for a way to download the Game Boy Advance (GBA) game, Pokémon Ruby and Sapphire or more specifically a game in the same vein, often referred to as Pokémon Indigo League, on your Android device. The game that comes closest to the 'Indigo League' experience on GBA is actually Pokémon FireRed and LeafGreen, which are remakes of the original Pokémon Red and Green games, or simply playing Pokémon games that capture the essence of the Indigo League era.