Alternate gang styles can be unlocked by completing certain in-game tasks. Gang styles can be changed at cribs or strongholds.

Gang style	How to unlock
Cops / SWAT	Complete all instances of SNATCH for Kinzie.
Deckers	Complete mission 37.
Hos	Complete all instances of SNATCH for Zimos.
Luchadores	Complete mission 43.
Mascots	Complete all instances of Prof. Genki S.E.R.C.
Morningstar	Complete mission 29.
National Guard	Complete all instances of TANK MAYHEM.
Space Saints	Complete mission 47.
Strippers	Complete all instances of ESCORT for Zimos.
Wrestlers	Complete all instances of TIGER ESCORT.