S1·E30 The Lightyear Factor

Zurg stumbles upon an alternate dimension where Buzz is evil (...possibly more evil than Zurg, himself...) and has taken over the universe. Zurg has Buzz, the evil one, capture Buzz, the good one, and trap him in the other dimension while they capture Star Command. Buzz's teammates (the good Buzz's, that is) venture into Zurg's Dreadnaught, thinking Buzz has gone insane, but, alas, are captured. Meanwhile, Buzz (the good one) is chased around by the alternate Mira and Booster (the bad ones). He gets a reprieve from the alternate Nebula (who isn't all that bad), who knows that Evil Buzz is working with Zurg. They team up in order to stop the bad guys. Team Lightyear is rescued, Star Command is saved, the Dreadnaught blows up, Zurg and his minions escape, and Evil Buzz is left floating out in space, ready for his revenge in ""Sunquake""...