The phrase 'mock enemy' is correct and usable in written English.
For example, you could use it in the sentence, "The troops practiced combat drills against a mock enemy." Here, 'mock enemy' is used to describe an artificial, simulated version of an enemy for the purpose of training.
Last month, General Petraeus, flanked by visiting generals from the American Special Forces, glowed as he watched in a hangar at the special forces' base as the Iraqis stormed a mock enemy-held house and simulated a room-by-room raid with live ammunition and stun grenades.
For their part, a group of SEALs conducted dive training alongside Greek special operations forces in Souda Bay, Greece, while others joined NATO troops in Germany as part of Exercise Saber Junction 17 for training in land operations, including mock "behind enemy lines missions" in a "simulated European village". .
Will you send a rush early on, not to win, but to mock the enemy?
Having donned recyclable 3-D glasses and seen the thing for myself, I'm not sure whether to mock the enemies of "The Lorax" for their cluelessness, to offer them reassurance or to compliment them for being half-right.
One letter written by Bin Laden and perhaps an associate went from criticizing the news media's coverage of Al Qaeda to commenting on a pre-Islamic tradition of satirical poetry called hija, which Arab tribes once used to mock their enemies.
Brat accused Obama of using the Bible and the "Christian tradition" to "bonk Republicans over the head with compassion" and "mock his enemies".
Hailed by supporters as the new Ataturk, mocked by enemies as a wannabe Ottoman sultan, Erdoğan now has the chance to shape modern Turkey to his liking and stamp his character, vision and conservative, neo-Islamist views on the country for generations to come.
However he then appeared in an online video in which he mocked his enemies' inability to destroy him and posed with an anti-aircraft gun mounted on the back of a truck.
