This can be done with 3 extra controllers easily, but i did it with only 2 extra controllers. I did in in quick play, and for some reason i had to remove and then re-add the cpu after adding my 2 extra players. For some reason it only loads the played characters. At least, it did for me.
I used the other 2 controllers to put their characters in one spot. Waited by them with my main until the cpu came close enough and i grabbed them with my hook, pulling them closer. Angled myself so i was facing all 3 but still real close, and hit RT. Killed all three, triggering the achievement to pop.