Twin Iron Scaled Cobalt Bone Apes.
A very rare mutated duo of the Cobalt Bone Ape monster species.
These twin monsters always worked together, splitting their duties between themselves. One was the 'combatant', and the other was the 'strategist'.
As for why the strategist was needed, it was because one of the twins always possessed a skill that empowered other monsters under their control.
These monsters were smart enough to not let such a good skill go to waste, so they always conquered any surrounding monsters and took control of them, and the strategist of the duo was the one who commanded these monsters in battle.
It was even better when the subordinated monsters were also Cobalt Bone Apes, as their skill usually had a greater effect on their fellow species.