To get to the special stage, when you get Roan (King Roan) to be part of your team, exit the Palace. When you get out, there are two places to go to, Raul Hills and the King Roan's palace place in the south. Go to Raul Hills. When you arrive, "Special Stage" will appear. You can train yourself until you are ready to leave.
Game Shark Codes
Master Code (Must Be On) 0E3C7DF2 1853E59EEE99F1DA BCD06FFA
Max Gold C1AA631A BCA99A82
Max Special Coins C1AA6326 BCA99A82
Max Magic Coins C1AA6322 BCA99A82
Infinite HP Ryudo C1AA64BC BCA9C292
Infinite MP Ryudo C1AA64B8 BCA99E6A