The screen that welcomes you to battle Kaecilius omits the fact that he can only be hurt by matching enemy strike titles. That information is really rather important because a player is likely to need a different team than their usual 3-on-1 damage dealing team. If you bring your big guns, you might lose or have to resign the match.
There is a pop-up screen that tells you his damage conditions, but I’ve never paid much attention to whether that arrives before or after you select your team. If after (which it likely is), I agree that that is something that should be improved.