XCOM 2
87 Achievements
GOG
Axles to Axles, Bolts to Bolts
Defeat a robotic enemy with a SPARK unit
10.4%
How to unlock the Axles to Axles, Bolts to Bolts achievement in XCOM 2 - Definitive Guide
This achievement is easily obtained by having the SPARK unit that you receive during the DLC "Lost Towers" mission kill a Derlict MEC (Not sure, but the turrets may count as well) considering the low health of the majority of the MECs and turrets in the mission.
However, the War of the Chosen expansion has a setting to integrate the two DLC packs (Shen's Last Gift, and Alien Hunters) into the regular gameplay, and as such the DLC story missions related to each DLC are not included. In this case, the easiest option would be to construct a SPARK in the Proving Ground and then use it's built-in rocket launcher to destroy a turret that is raised above the ground (such as on the ceiling of a building during the blacksite mission) as this not only counts as a kill for the MEC, but is also a guaranteed kill as turrets don't take fall damage like other units and instead, they simply die, regardless of health, making it a useful strategy for destroying even the strongest version of the turrets,
However, the War of the Chosen expansion has a setting to integrate the two DLC packs (Shen's Last Gift, and Alien Hunters) into the regular gameplay, and as such the DLC story missions related to each DLC are not included. In this case, the easiest option would be to construct a SPARK in the Proving Ground and then use it's built-in rocket launcher to destroy a turret that is raised above the ground (such as on the ceiling of a building during the blacksite mission) as this not only counts as a kill for the MEC, but is also a guaranteed kill as turrets don't take fall damage like other units and instead, they simply die, regardless of health, making it a useful strategy for destroying even the strongest version of the turrets,
Simply defeat any of the robotic enemies in the game with a SPARK unit. Only the killing blow matters. This will likely come naturally in the Lost Towers mission (see A Torch Passed).