Lego Batman 2: DC Superheroes Walkthrough Part 14 – Chemical Crisis, Part 2
Have Robin change into the Magnetic Suit and go for the Top Right section of the area. Go over to the blue pipes and walk up them. You can also have Batman climb the electrified ladder though Robin might not follow his lead properly.
Once in the upper area, head over to the left. There is a shiny blue bell on the left-hand side of this platform. Switch to Robin and move close enough to it to let him use the magnet to pull open the shutter on the floor. Switch to the charged Batman and head over to the exposed switch. Interact with it to pass the charge over to it and with that, reveal the next chemical vat you need to disable. Once the vat is disabled, a bridge will rise, revealing the way forward, with 3 henchmen on it.
Head across the bridge to the North with Robin in the lead. Use the magnetic powers of his suit to pull the shutter from the ladder to let it to deploy. There are a few things that can be exposed to the magnet to great effect up on the platform above. To the left and right, in the bottom corners you can find some constructs that can be quickly torn apart by Robin's magnet. But, as far as moving forward goes, once Batman and Robin make it up onto this platform, a bomb will blast the bridge in front of you apart. Some of the parts land on your platform. Head over to them and build them to get a small platform from which you can make it to the catwalk you need to reach next.
Follow the catwalk to the right and in the Top Right of the next platform you will find 3 items to tear about with the Magnetic Suit for chips. With that, head to the bottom right of the area. Wait a moment you will see the drums of chemicals moving along a track. Wait for them to get close then hop onto them. Wait until it lines up with the middle platform then walk or jump onto it. Go ahead and jump over to the next section to the right. Head to the bottom first and take a few swings at the U-valve there to get a lot of chips. After that, head to the top of the platform and use Robin's magnet to pull forward the barrels underneath the ledge. Climb the barrels to the next ledge above. Take out the various items here to collect a lot of chips. After that, head over to the left and interact with the Chemical Vat to collect the fourth sample. This will also get a few more of Joker's henchmen on you. Take them out quickly then head down the barrels and over to the right where they came from.
On the next on the platform, head for the electrically charged switch in the bottom right part of the area. Use Batman to draw the power out and then change over to Robin. There is a small platform just off to the right with the Hazard Suit on it. Have Robin change into it and it is time for a little puzzle. There are 3 pipes, each a different color. The far left one is Yellow, the middle purple and the right one is green. Using Hazard Suit Robin, hop into the different vats of colored chemicals. The front right one is yellow, the front left is purple and the one back one is green. Have Robin fill the Hazard's sprayer with one color at a time and spray it into the corresponding pipe. When all 3 are filled then the green chemicals will be cleared away by water. Switch over to Batman and climb up the bars on the far right side of the pool of water. Head for the top where Batman can draw away the electricity away from the bars. Change to Robin in his Hazard Suit now and have him climb up to the same area as Batman. Go to the bottom right. There you will see a switch covered in chemicals. Blast away the chemicals to use the switch to open the gate to the next part of the chemical plant.