When you enter Candy Floss’s chambers a scene will play and then the battle will begin. To take down Candy Floss you need to lower the shield he has around him. To do this, shoot the shield generators in each corner of the room that is lit up. At first it will only be one generator and then 2, 3 and finally all four. Each time one goes down, switch to your EVM and then fire at Candy Floss. No matter how much damage you give him, he will not die until all four generators have been taken down.
He will also launch gas clouds at you while he has his shield up, so make sure you keep moving and don’t stop. Once in a while when the shield goes down, there will also be unknown creatures that will come out from the hatches in the walls. Try to stay away from them and keep firing at Candy Floss until his shield goes up and then take them down.