You will get some help from new friends in this battle or at least Tidus thinks they are his friends at first. Try and keep attaking during this battle if you have to turns in a row either attack him both times or use a potion and attack. Eventually some people blast down the wall and one of them helps you beat Klikk. You will then learn how to use grenades(only the girl can use them and she is the only one who can steal so far). Use one of them and then steal a new one from Klikk. Keep this up and just let Tidus use potions when he or the girl need it and if neither of them need one then just make him attack. If you do this you should have no problem beating Klikk.
