In emerald where do you go to find legendary Pokemon?

First find the sky pillar and get 2 the top and bring your Mach bike to get to the top. The sky pillar is after Pacifidlog town and before the enterance to Sootopolis city. When you get to the top of the sky pillar rayquaza will be at the top but it will fly away when you see it. But when the two legendary from ruby and sapphire stop fighting go back to the sky pillar and catch rayquaza.