When you try to get into Hyrule Castle, get caught by the spotlights to fall, and get the Boomerang. Now head to the room with the bottles. Destroy these bottles with the boomerang in 1 shot, and you'll get a lot of Force Gems. Instead of grabbing the Hammer, walk out of the room, and head back in. The bottles will be back, so you can destroy them again. Continue this until you have 9999 Gems.
To unlock the final 5 Shadow Battle Arenas, complete Hyrulean Adventure.
After you talk to all the spies in the level and return to get the shovel, go back into the shadow world and switch the shovel for another Pegasus Boot or the empty item stand.
Leave the shadow world then the area with another item other than Pegasus Boots and go back down into the Dark World. The passage to the shovel will be blocked and the kid won't open it again. Talk to him and he will give you Pegasus Boots and you'll drop the other item. Keep picking up the other item and talk to the kid again for an infinite supply of the Pegasus Boot.
On the level Infiltration of Hyrule Castle, in the Near the Fields area, if you get caught an extremely large amount of times, there is a chance that your Links will turn invisible. There is also a chance that the sound of the game will go away. This does not affect the gameplay.
AT the end of a level when you and your friends are on the podium things and the game is totalling all of your force gems press and hold the "r" button to see yourself up close
you get up one and you can only use 2 in each one. up down up donw a b up a z
Complete the second stage of each level in multi-player mode to unlock the corresponding mini games.