A Battle Bear is a golem, a nonliving humanoid Unit capable of both siege operations and basic melee combat. Battle Bears are capable of throwing rocks, and these can be used against other units but are primarily used to destroy city walls. They can also push siege towers into place, further demonstrating their tactical versatility.
Battle Bears clearly share much in common with the other Cloth Golems, but it is unclear if one is a subset of the other or if they are simply 'cousins'. Their relationship may be similar to Gwiffons and Megalogwiffs, or regular units and Knights.