Overload is actually a non-sentient weapon platform created by the Minicons for Optimus Prime.
Packaging by Takara. The ability of Overload to combine with Optimus Prime was clearly shown here. In Japan, Overload is known as Ultra Magnus
It comes with Overload's main body, 2 missiles and Minicon Rollout
The size of Minicon Rollout is larger than the normal Minicons. He is the largest Minicon in the Armada series. Rollout is known as Magnus in Japan.
Rollout can transform to a gun for the bigger Transformers to use as weapon
Overload's alternate mode is a transport vehicle. Note Rollout is actually the cab in this mode
Rollout actually form the head of Overload, suggesting that Rollout is in control of Overload. This arrangement reminds me of Transformers Headmaster series.
Overload's bio data. Overload is actually packed with some heavy firepower as it will form a set of cannons for Optimus Prime. Since Rollout is in control of Overload, that should account the lack of intelligence in his bio data