The New Empire Gear uses a different monster system from many other Sentai enemy organizations. Instead of relying only on disposable monsters of the week, Gear deploys five recurring Beastnoids who return across multiple episodes as specialized field operatives.

The five Beastnoids are Psygorn the psychic, Messerbeast the flyer, Aquaiger the underwater warrior, Metzler the spy, and Juuou, Monster's powerful underling. Metzler and Aquaiger are destroyed midway through the series, while the surviving Beastnoids are later powered up.

For giant battles, Gear launches Mechagigans and later Neo Mechagigans. These massive robots serve as the main giant-scale threats against Bio Robo.