Hey! Both solutions so far explain this perfectly, but I recorded the little clip of when I got the achievement just as a frame of reference for anyone still stuck!
Head over to the area right outside of Joule's Crawler in the Granite Steps, where you'll find 3 Spiderbots level 2-3. Damage them with either RT or the T8NK as mentioned by Aeons of Blight, while continuously calling your corebot to you using the X button.
With any luck, you'll manage it like I do in the clip! This actually took me a couple of hours, as I seemed to have done it a couple of times with no pop! Hopeless commentary, but I hope the video does help!