There are six Autobots that come to Earth: Optimus Prime, Ironhide, Chromia, Mirage, Bluestreak, and Arcee. Chromia is Optimus' first lieutenant, and she's also the one that Nunally, Rivalz, Milly, and Shirley ride in.
Lloyd figures out that the Autobots need Sakuradite to function, though he doesn't completely realize that it's their power source. Because of this, he's able to use Gefjun Disturbers to set up an ambush that snares the Autobots, allowing Cornelia's army to move in and restrain them. Ultimately, most of the Autobots escape, but Ironhide is captured.
Also, Optimus Prime fights Suzaku in the Lancelot. When he sees Ironhide go into stasis lock and get hauled away, Prime flies into BERSERKER RAGE and beats the shit out of the Lancelot, stomping the cockpit flat and nearly crushing Suzaku.