Put this in as the name for a CAW:
Nick Name: ALL
Last Name (On the Left): WRESTLER
First Name (On Right): CLEAR
Middle: Leave Blank
Then, save the CAW. After that, all wrestlers in the game should be unlocked. After saving, you can then overwrite the CAW with another CAW if you wish and still have all the wrestlers unlocked!
To unlock every wrestler in the Japanese version of Fire Pro 2, go to wrestler edit, and name entry, and put in the following information in katakana:
Nick Name: ki chi ji (small)yo u ji
Short Name: ka ra
Long Name: a za bu ji (small)yu u ba n
Hit start, and it will change the name of the wrestler and play a fanfare.
Simply finish every step in training mode and you will unlock the trainer.