Simply pause and unpause the game at any time to gain all power-ups. There is an alternative way to become invincible. Beat the game and let the credits end. You are taken back to the Title Screen.

Screenshot: Credit: Milton Bradley, Natsume Inc. 2 / 8 3 / 8 4 / 8 5 / 8 6 / 8 7 / 8 8 / 8 2 / 8 3 / 8 4 / 8 ...