So you have seen cpu vs cpu and see nothing magic..
because if you’re not seeing anything special then you must be wrong in putting the setting, whether the potara is wrong or the game setting is wrong or you need to change your glasses. so follow my instruction.
1.set the enemy on very strong and the time on unlimited.
2.set the potara (make sure you have almost all of the important potaras – that’s more than 80% of the z items) right, what I mean is if you want to make goku stronger don’t put defense up 3 attack down 2 (that will make goku strong in defense but not attack) but put attack up 3 and defense up (to you) whatever.
3. along the way if you enjoy the ride you will find the “magic” of these z items that can add a special attributes to the character. this is what I mean by the secret. that there are more than just z items.