is anyone konw is it possible i can use gameshark code with the ps1 games in ps2 system? how about japanese games, is there any device i can buy to use cheat with ps1 games in ps2 system? anyone konw please post here or email me tyrant0303@yahoo.com

Greatly Appreciated ;)

Of course you can. The Gameshark2 comes with a PS1 disc just for that.