Clench is the Mini-Con partner for Galvatron, the reformatted and powered-up version of Megatron. After Megatron was reformatted, he decided to 'trade-up' his Mini-Con partner. Searching the globe over, Galvatron finally found the perfect Mini-Con partner in Clench, Leader-1's brother. Although Leader-1 and Clench share nearly identical transformations, Clench is ten times faster, stronger, and more powerful than Leader-1.
Bio and image taken from the 2003 Fleer Transformers Armada Trading Card set.