Lower each Legendary to red health and apply a status condition (sleep, paralysis, freezing) to have the highest chance of catching.

This pages also gives you info on Type, Ability, Level, and Moveset for all of the ORAS Legendaries. This Pokemon Omega Ruby and Alpha Sapphire Legendary Pokemon guide will give you the strategy and information you need to catch every Legendary Pokemon in the game. Omega Ruby and Alpha Sapphire feature more obtainable Legendaries than any other Pokeémon game.