For starters you will want to enter through the hidden entrance as you will obtain a vs through this path. Equip the vs shotgun and machine gun. as the fight starts shoot off her mini arms as this stuns her. Then shot her head with the shotgun. 2 good hits should stun her for a even longer time giving you time to unload your ammo on her head. Repeat this untill your either out of ammo or she destroys your vs. If she does dont fret theres a rocket launcher to the platforms to the left of the boss. use a machine gun to shoot the mini arms to stun her and then unload the rocket on her head. after this she should be dead as her defense isnt that high.