The top-half of Registeel's body is spherical and gray with a black stripe running down its "face". Its face consists of seven red dots in a hexagonal formation. It has black arms with three fingers each and cylindrical legs. While Registeel has been classified as a Steel-type Pokémon, its body is actually made of a material that is harder than any known metal. However, this material stretches and shrinks despite its hardness. Its body was tempered by pressure underground over thousands of years.
Registeel debuted in a brief cameo during the opening sequence of Destiny Deoxys.
A Registeel made a cameo appearance alongside the other members of its trio in the opening sequence of The Rise of Darkrai, where they all fired Hyper Beams that combined into an extremely powerful one.
A Registeel briefly appeared in PK18, where it sent Meowth and his cronies blasting off after they mistook him for a floating Pokémon.
Brandon used Registeel first in his battle with Emerald, where it squared off against the Hitmonchan the boy borrowed from Crystal. Though Registeel took considerable damage from the accumulation of many Fire Punches and was eventually beaten by a strong Sky Uppercut attack, it managed to cause its opponent to faint as well with a clever Toxic maneuver. It has not been seen since.
Registeel appears as an occasional stage hazard in the Ironworks Chamber of the Kalos Pokémon League stage. Appearing rarely, it will use Stomp to dislodge the swords embedded in the stage, causing them to fly upwards and damage fighters. Grounded characters will also take damage from Stomp.
This Steel-type Pokémon's hollow body is made out of an ultrahard metal, forged under pressure over thousands of years underground. It can appear in the Kalos Pokémon League stage, in the Elite Four's Steel-type chamber. Its Stomp attack will launch fighters on the ground, and even the giant swords mounted on the stage!
In the non-English European versions of Pokémon Diamond and Pearl, Registeel's sprite was edited because of its arm. The arm's original position is reminiscent of the Nazisalute. In Pokémon Platinum, the sprite was changed for all regions to the continental European variation (this change was retained in HeartGold and SoulSilver).
In Pokémon Ranger, Registeel was the only one of the three Legendary titans that has a Field Move. The other two have a Poké Assist instead.
In Ruby, Sapphire, and Emerald, there is an unobtainable Registeel Doll programmed into the game. It may have been intended to be obtained with the e-Reader.
Registeel may be based on the golems of Hebrew legend. The legends cast them as servants of higher powers and are said to have writing on their heads. When the writing is removed, the creature would be weakened, or even killed in some legends.
Registeel is the combination of the words regis (Latin for royal) and steel.