Roboquest

As you're running through the Canyon area, keep an eye out for one of the small enemies with a different paint job and a green eye, this is Buddybot. Instead of shooting him you need to run up to him and you'll get the option to pick him up like a weapon.

once you do so you should unlock the achievement and Buddybot will become available to use at the start of every run.

You can find Buddybot right before first checkpoint in the Canyons. Simply walk up to him and press to pick him up