METAL WOLF CHAOS XD

Mission: Space Station

Part 1: Use a weapon without energy ammo, and then use your Burst attack which should be about enough to finish off his first form. Remember to strafe and avoid his missiles.

Part 2: Run up the stairs, get the offensive augment and hide behind the building to put a few shots on him with the high firepower sniper.

Part 3: Don't have to move much, just snipe.

Personally I find fighting this boss on the ground level to be far too risky and unreliable to get this, feels like it comes down to sheer blind luck as to whether or not he hits you even if you are constantly strafing. I find it far easier to go to the upper level and hide behind one of those tall tower things(not the one right after you climb the stairs, the other ones farther back) as the bosses missiles won't be able to hit you if you stay behind there. Use the SC-RH Sniper Cannon to hit the target areas and then quickly go back into cover and wait for the missiles to stop before going for another shot, keep that up and you should get to phase 2. Then I recommend using your Burst attack and using your most powerful machine guns, as they'll do decent damage and destroy most of the incoming missiles, keep that up until phase 3 then unload whatever sniper ammo you have left on it and then use your assault rifles to finish it off if it's still not dead yet.