Robo Beam is the name for R.O.B.'s Neutral B Special Move. The attack is a short pink laser that does a short amount of damage (normally 5%) and has decent stun capabilities. The shots can be angled and reflects off of walls and floors. R.O.B. must wait a few seconds for the laser to recharge, or R.O.B. will shoot a weak, short-range laser. When the laser is charged, the red light on R.O.B.'s head will begin to flash.
Trivia
The flashing of the red light on R.O.B.'s head is a throwback to when the red light indicated that R.O.B. was ready for use with the NES.