They went on to fight in dozens of engagements throughout the Clone Wars, with much more efficient results than B1 units. These units were used for the first time on Geonosis where they were being designed and manufactured by the Geonosian and the Techno Union. The Super Battle Droid was originally produced on Geonosis by the Baktoid Armor Workshop near the dawn of the Clone Wars, though the genesis of their design lay in the Trade Federation's humiliating defeat in the Battle of Naboo many years prior, in which an entire army of B1 battle droids were disabled by a child (who would, ironically, become an evildoer himself when he was seduced to the dark side and became Darth Vader). They were used primarily by the Confederacy of Independent Systems.
They were enhanced versions of the B1 battle droids, and were designed to be sturdier, stronger and more deadly than their spindly counterparts. The B2 Super Battle Droids were a specialized infantry for the Confederacy of Independent Systems that appeared in Episodes II and III of the Star Wars films, as well as in numerous ancillary works and surrounding media.
~ Clone Troopers upon seeing super battle droids in Star Wars Battlefront II.