Well, I saw I havn't done every GRA challenges soo I thought I should go and do that. And one I was going to do was destroying Sentry bots and Mr Gutsys with Knuckles or iron pipes.

But after being in HELIOS, crashed vertibird and REPCONN HQ building. I couldn't find any. Someone know where there are any respawning?

btw, have them DLCs, every one of them.

The Crashed Vertibird, West of Searchlight Airport is one place they respawn. New Vegas Steel has respawning Mr Steels (variants of Mr Gutsy's).

Most of the Factories in Outer Vegas (Fiend areas and South of Westside) have robots. Cerruleuan (sp?) Robotics, H&H Tools are some of the places, but they don't always respawn in those places.