Mr. Freeze
This is actually a pretty simple fight. You basically just have to set traps for Mr. Freeze to stun his suit and then attack him while he is stunned. The only real problem is that you can't stun the suit the same way twice and you have to stun him five times. You just have to stay out of sight so you can set your traps and not get destroyed by his Freeze ray. And make sure you watch for his drones in the air. They will try and find you and ram into but usually you just have to put something between yourself and them so that they'll crash.
Start off the battle by luring him to one of the magnets. Stand out of his line of sight and aim at the magnet with your electric charge gun. When he gets near it, shoot the magnet and he will get stunned. When he's kneeling on the ground run up and pound on him until his suit actually takes damage (noted in the upper right) and his suit starts beeping. Then run away and hide.
Second, if he follows you up to one of the high sides, flip over the railing and hold on so you can do a ledge takedown OR if he stays below you can just get behind him and do a glide kick from behind. Once you do one of these, you can't do the other. Either of these will stun him. Then hit him for damage and retreat.
Third, do a takedown from behind. Just get behind him any way you like and crouch walk up behind him. Hit him with a takedown to stun him.
Fourth, go to the room that has the wires running into the water. Just inside is a button. Hit it when Freeze walks into the water to stun him but wait for the voltage to die down before you attack him.
Fifth, in this same room, off to the right (assuming your still in the room) is a destroyable wall. Go put explosive gel on it and wait for Freeze to come in the room. Then run and slide under the wall. If he comes out then you can slide back into the room. Just wait for him to get close to the wall and set off the explosives. This will give you your last stun. Go in and finish him off. Once his bar is exhausted, you'll have to burst his bubble. Punch him in the face a few times and that should do it.
