There's usually a fair amount of noise in the base, because otherwise it's quiet and boring, so more isn't really too out of the ordinary. But what is out of the ordinary is this weird metal stomping noise. None of the Grunts here have any sort of steel Pokemon, so that really shouldn't be something this Grunt is hearing right now.

So she'll just step out into the hall and...

“What is that doing here?!”

Okay, she was probably supposed to say something threatening, but she wasn't expecting to see a giant metal crab tank stomping through the hall. That's definitely not an everyday sight here.