One of the easiest Gold Trophies you'll find. All you need to do is add your new ally, Zhang, into your squad for the final Temple Ship Assault mission. I can confirm that he doesn't need to be in your squad a single time prior to activating the Gollop Chamber. The trophy pops as soon as you land on the ship. That's it! He doesn't need to survive the battle, fire a shot, or even move a muscle. I would advise uploading your save to the Sony Online Storage Cloud before starting the point of no return mission that way you can go back and finish with your proper squad (unless you leveled Zhang up and like him). Simple as that!