Pacific Rim strictly speaking does not feature robots battling against aliens, but "mecha".
Mecha are strictly speaking controlled by people. The term comes from Japan, and is the name of a genre of science fiction (especially anime) featuring such machines. However, confusingly the genre breaks down into subgenres of "Real Robot" (where the mecha and their technology are based on real-world physics) and "Super Robot" (where the mecha don't obey such laws and can do just about anything).
It's all rather confusing - and to be honest, I just wanted to mention this because I heard Sandi Toksvig refer to the machines as robots and not mecha on today's 15 to 1.
My opinion is that all robots are controlled by people. Working with an industrial robot, at first sight it seems that it is doing many things of it's own - however it does go wrong frequently and needs human intervention to correct the process.
On correcting the process it becomes clear that the robot isn't doing anything magical - essentiallying it isendlessly replaying a recording of physical movements a human made it do when setting up the process.
More sophisticated research robots such as Honda Asimo are exactly the same but have far more options to make based on the state of its inputs and sensors.