How do you catch Suicune without a master ball?

You can catch Suicune without a master ball by using a weakening technique such as status effects, such as sleep, paralysis, or freezing, to lower its HP and then throwing an Ultra Ball. You can also try using a Great Ball or a Timer Ball, which have a higher catch rate than a regular Poké Ball. Additionally, you can use the move False Swipe to lower Suicune's HP without knocking it out, making it easier to catch. Finally, you can also try using a Quick Ball at the beginning of the battle, as this ball has an increased chance of catching a Pokémon the first turn of battle.