Complete the following tasks to unlock the corresponding mission.

Unlock Mr. Blonde's Revenge Mission:
On the Agent, Special Agent or Perfect Agent difficulty settings complete ALL solo missions.

Unlock Maian SOS Mission:
On the Special Agent or Perfect Agent difficulty settings complete ALL the Solo missions.

Unlock War! Mission:
On the Perfect Agent difficulty setting complete ALL solo missions.

The following unlockables will change the ally and it's weapon on Co-Op IF it is a simulant.

Unlock Hit and Run (K7 Avenger):
Beat Carrington Villa: Hostage One in under 2:30

Unlock Hotshot (DY357 Magnum & DY357-LX):
Beat Area 51: Infiltration in under 5:00

Unlock Alien (RC-P120):
Beat Attack Ship: Nullify Threat in under 5:17

Unlock Pugilist (Unarmed):
Beat dataDyne Research: Investigation in under 6:30