Pokemon Alpha Sapphire/Omega Ruby -
How to get all of the Legendary Pokemon
The Eon Pokemon
The Eon Pokemon (Latios and Latias) can be obtained for free since you don't have to do anything to capture them the first time around. They can be found on Southern Island during the main story. Latios is available in Omega Ruby, and Latias is available in Alpha Sapphire. If you obtain the Eon Ticket from StreetPass, you will be able to capture Latios in Alpha Sapphire and Latias in Omega Ruby later in the game.
Kyogre and Groudon
These Pokemon can be found in the Cave of Origin just before the eighth gym. They will be in their Primal Reversion forms, but they will revert to their original forms after you capture them. Allow them to hold their special stone to return them to their Primal Reversions in battle.
Near the end of the Delta Episode, you will climb up Sky Pillar with another character. At the top, Rayquaza will appear. You must capture it to continue on with the story.
After capturing Rayquaza at Sky Pillar, you will then go into space to the asteroid coming towards the planet. Rayquaza will have Mega Evolved to destroy the asteroid. However, from the asteroid comes a black triangle that releases the Legendary Pokemon Deoxys shortly after.
If Deoxys faints during the first fight, don't be concerned! After the Delta Episode ends, go to the Mossdeep Space Center and take the stairs to the control room. You will find two assistants talking. They will tell you Deoxys's life signs have been found somewhere around Route 131.
After talking with the assistants, return to the Pokemon League and defeat the Pokemon League a second time. After the credits play out again, return to the Sky Pillar. Deoxys will be waiting for you at the top.
The legendary trio Regirock, Regice, and Registeel are well hidden in Pokemon Omega Ruby and Alpha Sapphire, but they can be found before completing the main story. A few steps must be done before their chambers can be opened.
First, you must capture a Relicanth and Wailord. Once you have those Pokemon ready, place them in your party along with Pokemon that know Dig, Surf, and Dive.
Travel to Pacifidlog Town and Surf west to Route 134 along the water currents. Your objective is to reach a dark patch of water you can dive into at the south part of the route. If you miss it, fly back to Pacifidlog Town and try again.
Dive into the dark water on Route 134 and follow the path to an inscription in the south. When you reach the inscription, resurface and follow the path to another inscription. Make sure you set Relicanth as the first Pokemon in your party and Wailord as the last when you enter this tomb. Use a Pokemon that knows Dig at the next inscription and then read all inscrptions inside the cave where the hole from Dig was dug. Once all the inscriptions are read, the screen will shake to let you know that the three chambers with the three Regis inside are open. If the screen does not shake, then...