From SmashWiki, the Super Smash Bros. wiki
Arm Rotor (
アームスピン,
Arm Spin) is
R.O.B.'s side special move. The attack causes R.O.B. to spin with an arm outstretched. The also attack lifts R.O.B. into the air slightly, allowing it to be used to aid R.O.B.'s recovery a bit (though this is rarely necessary). It deals minor damage (normally 4%), hits multiple times and has decent stun and
knockback. This attack can also
reflect any incoming projectiles that hit the outstretched arms. The move can be bit difficult to use as a reflector, as there is bit of delay before R.O.B. starts to spin his arms, thus requiring more accurate timing than the other faster reflectors. Finally, it can be extended by rapidly tapping the special move button. If R.O.B. moves left or right while performing this move, his torso will also bend.
[edit] Trivia
- Even when metal, the graphical effects of the Arm Rotor will still correspond with the arm color of R.O.B.'s palette.