He's easy when you no what to do.When he's small just keep hitting him, watch out when he does his shield, he does it your third attack so use your super speed to get away from him do this till a cut scene.It shows Superman throwing a box at Overcast, but this time he's massive. Go around the arena and keep picking up parts of the towers, try and stay in the air then throw it at him. Be careful he does his shield, but it's bigger. Keep doing this until he goes small.He starts to throw energy balls at you, and they chase you. Then redo the same process a couple more times he. There will be a cut scene showing Mongul jumping out of his chair to fight you. This is not as hard as it looks Mongul is strong but not strong enough. He blocks a lot so this might take some time. Keep attacking him until he brings some flying detonaters into it. Use heat vision one usually escapes and trys to blow you upthis happens twice at the end of all that there's a cutscene.
Press Start, then enter this code: CIRCLE, RIGHT, CIRCLE, RIGHT, UP, LEFT, RIGHT, CIRCLE
In the tip of the City there is a huge golden statue of Superman and in front of it is a glowing purple thing. Approach it and you will here a voice saying 'Abra Kadabra' and you'll turn into Bizarro. It's actually a challenge like in GTA, a rampage mission. You destroy as much as you can in a time limit. You turn back to normal after the timer runs out.
Warning: This contains spoilers, read at your own risk.
During this time, Metallo would have been a huge cyborg with mini robots flying around him. Your powers are useless, your heat vision has no effect nor do your breath and ice powers. You can't get near too. Your power would get drained. Remember what Jor El thought you on Warworld? Use the environment to beat certain opponents. Use the cars to beat him. There are two gas tanks lying on the streets when used they give a big decrease on Metallo's health. But after the first attack he'll hit you with his krypton blast, so don't pick a car right after throwing your first shot. Drain his life by throwing cars at him. After sometime a cutscene would show. He will fire a missile, you must intercept it. Like Metallo, you can't use your heat vision, so you need to grab it. Use your speed to reach it, then press X once you got near to it. After that a cut scene would appear. Metallo is done. A new chapter begins after.