Supreme Commander Trophy in Transformers: Devastation

The first few missions of the game will have you alternating between Optimus Prime, Bumblebee, and Sideswipe. However, you will soon gain access to The Ark, the hub area in which you can switch characters, create tech, and buy/sell/synthesize weapons. From this point on, choose to play as Optimus Prime for the rest of the game. After defeating Megatron at the end of Chapter 7, this trophy will pop on the stats result screen.