Do you have to use master balls catch legendary Pokemon in indigo can other like ultra and great balls?

Master Balls are not required to catch legendary Pokémon in the Indigo League, other Poké Balls like Ultra Balls and Great Balls can also be used. However, Master Balls have a 100% catch rate, making them the most reliable choice. Ultra Balls have a higher catch rate than Great Balls, but they are also more expensive.