The BattleBot (or Battle Bot) was the form of a Spiritual Weapon cast by Skud Derringer. It's shape was ever-changing, modifying to suit the terrain or comedic tone of an episode. It was capable of doing extra damage to an enemy, and was useful because it attacked on its own. This meant that Skud could create one and then move on to performing other actions, while the BattleBot attacked.
While Skud used his Spiritual Weapon previously, it only gained it's name as a "BattleBot" during The Storming of Mastwick, when The Tower of Grey fought Pyre. It was described as a "sword on wheels". It made frequent appearances thereafter, and was used solely in battle.