I don't think Ultron is a Transformer? But I never met him, so I don't know for sure.
If it isn't Starscream, it's probably still one of the Decepticons. It's still a robot that can disguise itself. It's still very dangerous. I don't think it can do anything organic, but jets, cars, trucks -- anything like that can definitely be a robot in disguise. Someone could definitely try flying through it. Or if you can get into the inner workings. Or somehow gum up the works with something sticky maybe. Might at least slow it down enough to take it out.