Unlocking Zeno and Dufort on Zatch Bell Electric Arena for Game Boy Advance is quite simple. Complete all the battles in the challenge mode of the game with Zatch and Kiyo in the normal mode. Make sure you play it for 60 seconds and you have at least more than 50 per cent of health left at the end of every battle. This is the only way of unlocking Zeno and Dufort in the game. There are many other unlockable characters and objects which you can unlock when you are progressing in the story mode of the game. There are no cheats involved in the game.