Flying Dragon cheats, and Codes for N64.
To play in the Rayomau Tournament you have to earn 9 medals.
Unlock Bonus Characters
Bokuchin -- Beat Bokuchin in a normal game.
Ryumaou -- Earn your way up to, and beat, the "Ryumaou Tournament".
To get Ryumaou on the virtual character select screen, beat SD Hiryu with Ryumaou. After beating it a couple of times you should get the "Skull of Devil King" as a random prize. This enables you to pick Ryumaou at the Virtual Hiryu select screen.
In the game select screen, go to Sd Hiryu. From there, fight in the circuit. Platinum characters will make cameo appearances before the championships. Each time you beat a platinum character you win a medal. If you collect all 10 medals you can unlock the Platinum characters for your own use.
Very Easy Difficulty Level
Highlight the "Easy" difficulty option, then repeatedly tap Left until "Very Easy" is displayed.
Very Hard Difficulty Level
Highlight the "Hard" difficulty option, then repeatedly tap Right until "Very Hard" is displayed.