CPU characters in battle mode
At the battle mode character selection screen, hold Z and press A to use the CPU characters.

Music option
Successfully complete story mode to unlock the music option.

Battle royal mode
Win the gold cup in survival mode to unlock battle royal mode.

King and knights mode
Win the gold cup in battle royal mode to unlock king and knights mode.

Key trial mode
Win the gold cup in king and knights mode to unlock key trial mode.

Score attack mode
Win the gold cup in key trial mode to unlock score attack mode.

Alternate title screen
Successfully complete the game to change the title screen to display one of Pommy's different levels with a blue background with clouds.

Guardian Boots
In Starlight, after you get the lightning bombs, return to the start. Enter the next area. Push on the middle left, where a golden statue used to be. You should enter a room. Lightning bomb the platform to get the Guardian Boots. You can now permanently kick bombs.

Guardian Gloves
In Planet Horizon, after the area where you defeat Ashtarth, go down the stairs. Get the bomb throw, and go to the door in the "Up" area (not the one you came from). Get the Remote Control (bomb the statue and collect it) and step on the two buttons. Go back. Enter the door on the right. Move right, then put the statues on the buttons as was done during the first time in Planet Horizon. Wind bomb to the elevator platform. Throw a bomb downwards and press Z at the top of its arc. It should take away a small pillar object. Return to the beginning of the room. Go up the stairs. Wind bomb yourself across. In the next room, lightning bomb the platform and grab the part to get the Guardian Gloves.

Guardian Vest
In Aquanet, just at the beginning on your right are three pillars. Use an earth bomb here. Enter the hidden doorway on the left. Lightning bomb the platform to get the Guardian Vest.

Guardian Helmet
In Neverland, go to the point with the lava strip in the middle and two knights on the sides. Use a dark bomb at the end of the strip, which resembles a small door, and it will open. Use an ice bomb to freeze the lava in front of it, then walk through. Lightning bomb the platform to get the Guardian Helmet.