The cover of World’s Finest 156 (March 1966) makes this look like a full out Joker/Bizarro team up, but Hamilton, Swan and Klein devote far more time to the Bizarros.
Batman and Superman head into space for a mission, letting Jimmy Olsen and Robin know. But Bizarro is monitoring Superman at that moment. The Bizarro Batman makes his first appearance, and they head to Earth to substitute for the heroes.
Each builds an extremely public version of their respective secret headquarters, and then go around undoing previous deeds of Superman and Batman. Robin and Jimmy Olsen fret, but have no real function.
Bizarro and Bizarro Batman do break the Joker out of prison, and help him commit a jewel theft.
When Superman and Batman do return to Earth, the Bizarros have no problems about handing over the Joker, and think the gems are ugly and worthless. They intend to stay on Earth, so Superman and Batman head to Bizarro World and start fixing things, which upsets the Bizarros, who return home.
A fully enjoyable Bizarro World’s Finest team-up. Bizarro, and Bizarro Batman, return in Superman’s Girlfriend Lois Lane the following year.