To start the second Riddler trial, you need to head to Chinatown. After you get there, drive into the garage and wait for the elevator to get you below. Also here, you use the batmobile, but not only that and you will not have to race against time. The plan is to reach the generator, which you can use the hoist on, and for this, you will have to use the mechanisms around you.
Climb onto the nearby elevation and use the combat mode in narrower spots. Your destination is the movable ramp. Stop on the ramp and use the Riddler blockade to deactivate the obstacle that has been blocking it. Thanks to this, you can manipulate the ramp freely. Stop in the lower part of the ramp, gain speed and use the charger to get to the ledge above.
Turn right, use the blockade to extend the platform closer to you and park the batmobile there. Get out of the car and find the pressure plate shown in the above screenshot which you need to stand on. This will extend the platform in the middle. Activate the batmobile remote control (you cannot walk off the pressure plate) and drive the batmobile onto that ledge. Then, use the Riddler blockade to extend the third platform (the first one will slide back in, but this one is already behind you). Walk over that platform to reach a new stable ledge.
Drive onto the new movable ramp and start using the blockade to hide the blocks that are sliding out. After the ramp turns up, as far as possible, make sure that the bigger platform behind it is out (if not, use the blockade). After that, back up as far as possible, drive onto the ramp and take the charger- aided jump .
You now only need to reach the interactive catch on the generator. Use the hoist on it and start revving up the engine - you need to keep the meter within the orange field.
You can now return to Batman and go to the pressure plate near the panel with buttons. Just like in the case of the first trial, remember where the green bulb is, switch to Catwoman and find the corresponding capsule with the key (the above screenshot). Approach the green door now and listen to Riddler's commentary. You can now cut back to Batman and leave.