The guards do a daily check to see if the tracker that was placed in your rib cage is still there, they do this by having you lift your shirt and feeling your ribs.
The scientists rarely ever test you but when they do it's usually small things like seeing how you interact with others or putting you in a fighting ring to see how far your abilities can go, so far you have no limits. Nothing you do surprised them anymore.
There are other subjects with powers, at least 20 other subjects.