Yes he is playable on psx/psp, even in field you can use him , but the problem is it take a lot of time, cloud skeleton field is not "compatible" with sephiroth's , so it can cause bugs, but it can be fixed by modifying ALL the field data of the game ( very long) , but still possible. Im making a mod for psx/psp where he will be playable instead of vincent ( their skeletons are compatible so no need to modify other datas) in field and in battle with his final appareance, ( with no shirt hi-res), but now i understand that hacking the data for PSX is really harder than PC.