First do the "Cheat Mode" code. Then choose Raos (the boy on the left). Go to the store, stand before the Crystal and press A. You'll get a free Armor. Go back to the house and choose Raos again, but this time, wear the armor you just got for free. Leave the house and deplete your magic points completely. Go back into the house, place the cursor on the grandfather painting on the wall and at the same time hold Left + B on controller 2 & Right on controller 1 (the cursor should stay in place). Now, while holding, press A on controller 1. If done right, a sound should be heard. Now you'll have max items and if you die, you'll come back to life.
Music test
Move the pointer to the painting on the wall in the house at the start of the game. Press A on controller two to hear various game music.
No damage on spikes
Hold Up while walking on the spikes.
Passwords to start with everything
On the password screen type these codes in
C4TB RSSH 6RXC 1TJH
CUTK 3NFT YWMC WJVU
Sixteen of all items
Hold Up/Right + A + B on controller two and Down/Left + Select on controller one at the title screen. With all those buttons held, press Start on controller one. A sound will confirm correct code entry. Select Roas (the boy character), move outside to the tree shop. Try to buy a crystal, then return home. Select Roas again, move outside, and use all available magic energy. Return home and position the finger of the on-screen pointer on the eyes of the picture hanging on the wall. Hold Left + B on controller two and Right on controller one without moving the pointer. While all those buttons are held press A(16) on controller one. Sixteen of each item, except crowns and the dragonslayer sword, will be available.
View Ending
Note that you must use a 4-player adapter for this. Use the same process as for the "Cheat Mode & Codes" cheats above, but press Left, Right, and A on Player 3's and Player 4's controllers.