Monsters can be unlocked by winning the final game of the Black & Blue League. Their special abilities are called "Intimidation". This affects the passing game more, especially for players using QB Vision. Once it is activated, your receiver's icons are turned into question marks. The result is that the QB cannot hot route or smart route anybody, and locks the primary receiver so your QB vision cannot lock on properly. However it has no consequence in the actual throws. It may lose accuracy. For example, if you are doing Singleback-Normal, PA TE Corner, the primary receiver is the tight end, when you are intimidated, his route is locked. You cannot move him, and you are stuck with him as a primary target. Your QB will fixate on him when you snap the ball (unless you swivel your head by moving the Right Analog-stick, but you cannot lock on anyone else for an accurate throw). Despite the receiving icons being spooked, when you press Square for this play, it will head towards your correct receiver. To counter, use the following strategies.

Control your wide receivers and run your own routes. If you do like the preset primary receiver, control him, but change your routes.

Turn QB Avoidance on. It lowers its effectiveness somewhat.

Make shorter passes where you can make accurately without QB Vision.

Use a running play. Blocking is not affected by it much.

Change formation or change play, but it will not change the primary receiver.

Defensively, this merely messes up coverages. If yopu are playing as Monsters, the special abilities are initiated randomly and automatically.