You can use focus target to see other targets you need to observe either health or stacks of debuff. For example, in turn 2 of Coil, tank can set the other tank focus targets so you know exactly how many stacks they're at if you're not used to look at the party window. This allows you to watch status and timer (most important) of another party member for important mechanics like rot. I don't know how you set it on PS3 though as I play on PC with controller and have the keybind to a key on my keyboard.