Doflamingo possesses an as-of-yet unnamed ability to control people's bodies like puppets. He can make his victims move as he wants by moving his fingers accordingly.
Doflamingo mainly uses this power to force comrades to fight (and kill) each other, while Doflamingo himself sits at the sidelines and watches.
It is currently unknown what the limitations of his abilities are. Every one of his victims being controlled was unable to resist his powers and therefore was rendered completely helpless. This ability is even powerful enough to stop the physically strong "Diamond" Jozu in his tracks, preventing him from further attacking Crocodile.
In the One Piece: Gigant Battle! 2 New World, this has been classified as a Paramecia Devil Fruit. However, it has yet to be confirmed in a canonical source.