Marty's Memory requires you to destroy 3 barricades with Stardust in the underground area below the boss arena during the boss fight and go to the middle where the rays of light converge.

God's Memory requires you to destroy 6 anchors. After 5 are destroyed, begin the fight with God. When he opens his mouth, go inside and destroy the final anchor.

The Fallen King's Memory requires you to stand on E6 for 33 seconds during the boss fight.