Hidden level:
Hold Z and press R, A at the title screen to display a password screen. Press Z, A, A, B, R, L at the password screen to start the game at a hidden stage in the Angelica's Temple level.

Hint: Safety from Angelica:
If you land on a square with another player in Angelica's Temple, you will be safe from Angelica. This allows the temple to be easily explored.