To play as Ryuju Yamazaki and the Jins, finish the game and save it. Restart the program, choose "LOAD SAVE DATA" and then choose "NEW GAME." At the character selection screen, highlight the following characters while pressing LOW KICK once on every character:

Terry->Hon Fu->Mai->Geese->Bob->Sokaku Mochizuki->Andy->France->Joe Higashi->Blue Mary

If it is done correctly, a message will appear.

To use Tiny Fighters in VS mode, hold both 1P & 2P 's LOW KICK and HIGH PUNCH when confirming the fighters.