Batman Arkham City: Meltdown Mayhem Batman

This is the same pattern I used when getting my best time of 27.95s which you may watch here: https://youtu.be/omB6jurdc_M. The only difference is that I do the other one fast enough to catch the last guy still on the ground. A few pointers...
1) Get the Sonic Batarang off as fast as you can. With practice, you can learn to hit Prisoner #1 with the Sonic Shock Batarang, further decreasing your score.
2) As I watched the rendering video, I realized that it might be possible to only shock #2 instead of using the Batclaw as well since it seems he gets knocked off the stairs by the REC gun. If I'm right, you should be able to shave a second or two from even my score with a little practice. And since as far as I can tell, 27.95s is the fastest time on YouTube, this would for sure be a world class score.

If you simply want to finish the challenge with a decent score, what I've shown you will do it fine. Looking for your PB? Keep practicing until your score is sub 30s and you'll have a world class time =)