The R.O.B. Squad is a group of enemies in The Subspace Emissary that is found exclusively on the Isle of the Ancients in the Research Facility, the Subspace Bomb Factory and Outside the Ancient Ruins. It could be considered a robotic counterpart to the Koopa Troop.
Aside from defending the Isle of the Ancients, the R.O.B. Squad served a vital role in Tabuu's plot. Whenever the Ancient Minister dropped one of the Subspace Bombs, two R.O.B. Sentries were required to arm it, being sacrificed in the subsequent explosion. The R.O.B. Squad was initially under the command of the Ancient Minister, but during an attack on the Subspace Bomb Factory, Ganondorf took control of them, ordering them to attack the Ancient Minister. This cut scene is the only time R.O.B. Sentries can be seen using their beam firing ability. When the Isle was destroyed, the R.O.B. Squad was wiped out along with it, with only the Ancient Minister/R.O.B. surviving the ordeal.
Three types of R.O.B. constitute the R.O.B. Squad, each with their own unique design and attacks. Their trophies are collected by use of a Trophy Stand.
Main article: R.O.B. Sentry
The R.O.B. Sentry is the R.O.B. Squad equivalent of a Primid, attacking with melee moves. Like Primids, there are variations of the R.O.B. Sentry that attack in different ways. According to the description for the R.O.B. Blaster trophy, R.O.B. Sentries are equipped with beam firing capabilities, but they choose to participate only in hand to hand combat.
Main article: R.O.B. Blaster
The R.O.B. Blaster is a gray and white member of the R.O.B. Squad. Its color scheme is based on R.O.B.'s North American design. Unlike the R.O.B. Sentry, the R.O.B. Blaster chooses to use its beam firing capabilities, attacking from afar. There are two varieties of this unit, one which remains stationary and another which moves around by hovering with its booster rockets. The mobile version can be difficult to battle as it is the fastest member of the R.O.B. Squad and will attack from a distance.
Main article: R.O.B. Launcher
R.O.B. Launchers have a very dark green body and the cord on their backs is light blue. One of R.O.B.'s alternate costumes is very similar to this color scheme, but the cord has a different color. R.O.B. Launchers fire tracking missiles at the player which deal 21% damage per hit. The missiles cannot be absorbed as they are physical projectiles, but they cannot be reflected either. They are arguably the toughest members of the R.O.B. Squad.
The Giant R.O.B. has only one appearance in a cutscene playing before Outside the Ancient Ruins. A frightened Olimar watches his Pikmin as they fruitlessly attempt to attack the R.O.B., but it kills most of the Pikmin with its Arm Rotor. Captain Falcon then ejects from his Blue Falcon and destroys the R.O.B. with a Falcon Punch.