There is no "easy" way unless you:
A- cheat
or
B- use a master ball
I would recommend to catch him by weakening him down to red then just keep throwing ultra balls at him, even if he uses rest.
*note: it is best to save the game near him and before you verse him. You will most likely not catch him on the first try.
I haven't played emerald in a while, but i believe you have to catch raquayza first
no it's not possible to catch rayquaza in silver but if it is a hacked version you can catch it
In the Mirage Tower nefore you get the Fossil
erwater cavern surrounding sootopolis city
Yes, You can catch Groudon in Pokemon Emerald.
You can't catch one in Pokemon Emerald.
No you cannot catch Entei in Pokemon Emerald.
You can't catch a Bellsprot in Pokemon Emerald. You trade it from Pokemon Leafgreen!
There are many Pokemon you catch that are similar in sapphire and emerald but there are many Pokemon emerald can only get and not sapphire.
Cressilia is a 4th generation Pokemon so you can't catch it in Pokemon Emerald.
You can't catch or obtain other trainers Pokemon in emerald.
you cant. You can only catch it in Pokemon emerald, but, you cant catch latias in emerald.