If you look on the front of the Tekken CD case and if you look underneath law and king you will see a blue guy. I think he is called dragon fighting jack but you can not unlock him. I do not know why.

While the game is loading hold Up + L1 + Triangle + X on controller 2

During the demo hold L1 + L2 + R1 + R2 + Down View Anna in demo mode

During the demo hold L1 + L2 + R1 + R2 + Down-Left View Armor King in demo

During the demo hold L1 + L2 + R1 + R2 + Left
View Ganryu in demo mode

During the demo hold Down + Right View Jack in demo mode

During the demo hold L1 + L2 + R1 + R2 + Down-Right View Jack P. in demo mode

During the demo hold Up View Kazuya in demo mode

During the demo hold Down + Left View King in
demo mode

During the demo hold L1 + L2 + R1 + R2 + Up-Left View Kunimitsu in demo mode

During the demo hold Right View Law in demo mode

During the demo hold L1 + L2 + R1 + R2 + Up View Lee in demo mode

During the demo hold Up + Left View Michelle in demo mode

During the demo hold Down View Nina in demo mode

During the demo hold Up + Right View Paul in demo mode

During the demo hold L1 + L2 + R1 + R2 + Right View Wang in demo mode

During the demo hold Left View Yoshimitsu in demo mode

With any character beat every character and the sub-boss

After you see the number of ships you've hit on the scree, press the Select button. You should hear a sound indicating it worked. You will now be able to replay that stage. Note: if you try this on the last stage you will be returned to stage one.

You have to Beat 8 stages in Galaga.

With any character, beat every character up to and including Heihachi without continuing.