How do you find the 7 treasures

Defeat Groudon to get the earth cymbal at shimmer hill. Defeat Kyogre to get the water monica at bottomless sea. Defeat mew to get the grass corronet at mystery jungle. Defeat Giratina to get the rock horn at world abyss. Defeat Raquaza to get the sky melodica at sky stairway. Defeat Heatran to get the fire drum at giant volcano. Defeat Articuno to get the icy flute at mt. avalanch.