Robots can become "groggy" after having several of their punches countered. ("Countered" in this sense means being hit by a punch just as the robot is performing a move.)
Once groggy, robots will recover after a certain amount of time, but you can help them recover more quickly by rapidly pressing the face buttons. The effort required for recovering is dependent on that robot's Resilience value. A value of "1" will require around 100 button presses, whereas a value of 10 requires somewhere between 40-50.