In order to unlock Legendary Pokémon encounters, a player must obtain ribbons by defeating gym leaders. Each ribbon represents a Pokémon region and unlocks its respective legendaries. All gym leaders in a region need to be defeated. You can track your progress from your profile by checking your obtained badges. In the past, elite 4 members, champions, battle frontier brains, and battle maison members had to be completed for all legendary Pokémon to become obtainable but is no longer the case after a v4 update.
