'Hidden machine' is just its name. There's certain... we'll call them moves that pokemon can learn that have utility outside of battle. Ones that allow them to move large objects or destroy boulders or swim up waterfalls or fly their trainers places. A rare few pokemon can learn them on their own, but most of us have to get the 'hidden machines' by defeating various gym leaders and those 'hidden machines' are used to teach the pokemon how to Surf or Fly or properly use their Strength.

[Or you can borrow a friend's and then lend them to some of your fellow Rockets in turn, like Steven did.]

But even then, they'll only use these moves in battle unless you can defeat other gym leaders to be granted permission to use them in your daily life. [He examines his hands.] I haven't seen a Jenny chase down an unlicensed Flyer, but I'm sure they'd try.