How I should catch Latias?

Question

How do I catch a Latias if I used a Master Ball on a Kyogre? Do I get another Master Ball?

Answer 1

You can get another Master ball from the Lilycove department store lottery, but only if an ID number of your pokémon matches the lottto number perfectly, so it's not easy.

Otherwise, all I can suggest is trapping Latias in play (Use mean look) and then just weaken it carefully before trying to capture it like any other pokémon.