Instructions
Go to Pacificdlog Town in the islands to the south-east of Hoenn and use a Pokemon's Surf move to head east on Route 131.
Follow the northern side of the route until you come to a gap in the rocks where you can double back toward a beach.
Head up the beach to the Sky Pillar and climb to the top. Use your bicycle to get across the cracked floors inside.
Find Rayquaza at the rear of the top floor of the Pillar and approach it to start a battle.
Use Ice, Rock or Dragon-type Pokemon or attacks to wear down Rayquaza's Health Points. It cannot be damaged by Ground-type moves and is resistant to Water, Fighting, Fire, Grass and Bug-types. Use a Master Ball or the best Pokeball you have to catch Rayquaza once its health bar is very low and turns red.