Legend of Zelda: Four Swords Adventures (The)

Final 5 Shadow Battle Arenas
Complete Hyrulean Adventure.
(Thanks to darth_hamster@hotmail.com)

Infinite Force Gems
Get caught by the spotlights in the level, Infiltration of Hyrule Castle, at the 'Near the Fields' area. Fall down the hole and get the treasure chest and boomerang, Now, go to the final cell (the one with many pots and several switches). Create a line of Links and shoot your boomerangs, and you will collect lots of Force Gems. Leave the hammer for now. Leave through the southern door, then re-enter and get the Force Gems from the pots again. Repeat for as many Force Gems as you want.
(Thanks to darth_hamster@hotmail.com)

Tingle Tower Mini-games
Complete the second stage of each level in multi-player mode to unlock the corresponding mini-games.
(Thanks to darth_hamster@hotmail.com)