Star Ocean: The Divine Force features a fast real-time battle system. You control one character, but you can switch to three others freely. The allies you don't control will automatically attack but do they use all the moves in the arsenal? Do they use the Chain Combos you have set them? Here's a guide explaining if allies use Chain Combos in Star Ocean: The Divine Force.
Do you need to change Chain Combos for party members in Star Ocean Divine Force?
Yes, allies use the Chain Combos set in the Chain Combos menu in Star Ocean: The Divine Force. If you still need to add new moves to party members' Chain Combos unlocked via the skill tree, allies will only perform the actions in their Chain Combos and nothing else. AI-controlled party members cannot access all learned moves and can't use them as they please. They are limited to what they have equipped in the Chain Combo menu.
At first glance, the Chain Combos may have been for when a player takes control of them during battle, so you have access to the Chain Combos you have set. Unfortunately, that is not correct. Suppose you have deleted all the moves in their three Chain Combos, if so, your ally will do nothing in combat. They will move around but not attack. So you have to manually set each one for party members to participate and help you fight.
You need Chain Combos on all party members to utilize them in battle. If you wanted to increase the difficulty arbitrarily, remove everything from allies, so you must do all the work. If you only give them the basic attack, their damage output is abysmal.
For more Star Ocean: The Divine Force games, check out How to get Game Meat in Star Ocean Divine Force and How to find the quest log in Star Ocean Divine Force at Pro Game Guides.