Gyro (ジャイロ, Jairo) is R.O.B.'s down special move in Super Smash Bros. Brawl. The attack encompasses a spin toy that R.O.B. fires. It is chargeable; the longer it charges, the stronger and faster it becomes. A fully charged Gyro normally inflicts 18% damage and has high knockback. After being launched, it can be picked back up and thrown at the opponent, inflicting 10% damage. An opponent can pick it up as well. It also acts like the Unira in that it will still cause damage on contact as long as it is spinning. Each R.O.B. can only have one originating gyro on the screen at any time and can use Gyro again as soon as the previous gyro leaves the screen. If the move is attempted when R.O.B. cannot reuse his gyro, he goes into his Gyro-charging stance and makes a motion with his arms as if to spin a gyro, but no gyro appears. Much like Donkey Kong's Giant Punch and Samus's Charge Shot, Gyro does not attack instantly when used. Instead, its initial use begins a charging process. The move must be performed a second time to fire the gyro.
The "Gyro" is essentially a spinning top. The R.O.B. accessory for the Nintendo Entertainment System would spin the gyros on a spinner and use them to press buttons to activate in-game effects for the game Gyromite; the button would remain pressed only as long as the gyro retained enough speed to remain upright. The concept of the move in Brawl is exactly the same as when the gyros were spinning in the Spinner, but throwing the gyro is a new feature added in Brawl.
The "Gyro" in Brawl is designed exactly like the real Gyros, but the spinner seem to be based on the "Gyro holder", where the Gyros had to be placed for R.O.B. to pick them up, rather than the actual spinner. Another difference is that to play Gyromite R.O.B. has specific hands designed to pick the Gyros, while in Brawl he picks them with his regular hands, based on his Stack-Up hands.