No! Bad Mr. Dinkles! Bad!
A Grivelnox, possessed by the Loki Master, A4O
Grivelnoxs were apex predators native to Rykan V, and were one of the most dangerous creatures in the galaxy due to the Grivelnox's natural ability to augment its body by digesting other creatures.
Grivelnoxs are incredibly dangerous creatures, alongside it's already great physical power, it's ability to augment its body by digesting other creatures makes it a fearsome opponent. The Loki Master seemed to consider it the greatest of all the monsters he had collected, as he chose it as his host.
A Grivelnox serves as the final boss in All 4 One, and thanks to being possessed by the Toranux Spirit, is a much more capable fighter than normal. During the first stage of the battle, it ate a Wigwump, giving it all of the Wigwump's fire powers. In the second stage, it ate a Light-Eating Z'Grute, giving it all of the Z'Grute's electrical powers - including regeneration.
In the final phase of the boss fight, you must trap it by activating switches which are triggered by launching a player at them with the Vac-U 4000. Dr. Croid and Nevo then zap it with an extractor gun. The Loki Master, who has been possessing it the whole battle, is then able to be fired at.