―When he's in bot mode, Grimlock is one of the smartest, smoothest talking bots around. In T. rex mode, he's less about the talking and more about the smashing.
Grimlock is the legendary king of the Dinobots. Always looking out for his friends, Grimlock has two personalities. In robot mode, he is one of the most talkative and smartest Autobots. In T. Rex mode, its a different story. Grimlock rerouted his own circuitry to be more powerful while in his dinosaur mode, causing him to be more prone to smashing things than talking.