What is the ideal counter for a Hammerhead in terms of rock/paper/scissors and vice versa to what threat is the Hammerhead an ideal counter?

A dedicated anti-capital ship such as a Retaliator would be able to fight the Hammerhead effectively by tackling it from outside the effective range of its guns. The Hammerhead is intended to defend other ships from attack fighters with its many turrets, so massed waves of small ships stand little chance against it.