Beast Master (ビーストマスター), English name Robo-Emperor, is the first WEA-type Medarot. As of most WEA-Types, his name has a word meaning "leader".
Beast Master's type is weapon, and his design is based to make it look like full of weapons. Aside that, Beast Master's design is based on the mantis shrimp. Its Death Blast part allows it to shoot a big Press attack, this is, it allows to heighten enemy's gravity, thus damaging it severely. Its Death Bomb shoots many types of Napalms at once, and its Death Beam shoots a powerful Beam at once. Overall, this Medarot alone could sweep out entire teams by itself in no time. However, Medarots like DonDoguu, more specifically, the DGU-types could render this Medarot unable to attack in later games (not considering the chance it could use a Medaforce). In the first games, however, the DGU-types could only negate its Napalms, the HNI-types could only negate its Beam, and Shell Cushion could negate its Press, so back then Beast Master was a destructive beast.
In the animeKikuhime's Peppercat but she couldn't use it due to the weight of the Decoy Crab. As a result, she lost to Escarloader.
Later, the whole Medarot was used by Sakekaasu. It caused a lot of riot, and both Metabee and Rokusho battled against it. Ikki lent Rokusho his Fencing part during the battle. When both Medarots were weakened, Metabee used the Medaforce for the first time, defeating Beast Master.
It appeared again when Dr. Akihabara has exposed Beast Master outside the lab. Karin took him and placed Saintnurse's Mermaid Medal on him. She disguised herself as a Roborobo and placed a doll of herself on Beast Master.
In Episode 51, Dr. Hebereke's clones have Death Bomb and Death Beam in their arms.
In the games
In Medarot R
Medal God has 2 Beast Master with God Emperor as his leader.