For the uninformed, a Battle Walker Takedown requires you to perform a takedown move (using
) on an enemy while using the stilts. Naturally, you need the battle walker for this (you can either get it in story mode, or in the Venus Transportation District). There are plenty of places to try this, but if you're having trouble, let me show you a very easy place to do it.
Go to the Manhattan Bunker District and play until you see one guard on a walkway looking in the other direction (about halfway through the mission). Double Tap
, walk up to him, hit
, and the achievement is yours. Here's a clip of me doing it:
Hopefully this helps some people. If you see a mistake or have something to add, let me know and I'll edit (don't just downvote with no comment, that doesn't help anyone).