Let's look back at these tales!
World's Finest Comics 94
This case has Superman hunting down Lex Luthor, but keeping Batman and Robin at a distance, instead working with a new hero, Powerman. Batman and Robin recall the first time they worked with Superman, where they handled criminals for Superman because of the criminals having Kryptonite, and Superman's protestations of their actions, because of his worry the Dynamic Duo would get hurt. This parallels this current case as well....when Batman and Robin help capture Luthor and Powerman's secret is revealed!
Secret Origins collection of 1961 (and in its various recollections as well, and in the World's Finest Comics Archives, Tradepaperback and Omnibus, and even in Batman: A Celebration of 75 Years).
To be fair, this wasn't really their first meeting, but, Superman and Batman did learn each other's alter egos (of Clark Kent and Bruce Wayne) as they worked to solve a crime on board a cruise ship, with Batman saving Lois this time, while Superman stopped a fire (though, at the end, Robin got the best prize of all!).
To be fair, this wasn't the first meeting of Superman and Batman (it gets complicated, as revealed here), but it is a key story, worthy of a Millennium Edition reprint (as well as a few more, including being in the Superman: A Celebration of 75 Years).
World's Finest Comics 71
This time around, after Superman rescues Batman and Robin from a Bat-Plane crash caused by criminals, he's a little careless, and Lois sees Superman change into Clark Kent! Superman and Batman disguise themselves as each other as part of a plot to confuse Lois, but Clark as Batman gets felled by Kryptonite, with Bruce as Superman going to his rescue (after trying to convince Lois that Bruce Wayne is Superman). Lois also shows up, and sees Clark as Batman, and all the confusion gets Lois to back off from identity snooping for bit.
This issue, along with leading up any collection of Superman-Batman team-ups has its own Millennium Edition reprint as well, including the Green Arrow and Tomahawk stories as well.
World's Finest Comics 76
Metropolis and Gotham are competing to host a science convention, so Superman and Batman switch cities to see who can perform the most good deeds in a night, with the winner getting the convention in their city. Superman does 4 in Gotham, with Batman getting 5 in Metropolis, so the convention goes to Gotham. Good thing, as Batman needed it because an invention at the convention radiates Kryptonite, weakening Superman (though, thankfully the machine self-destructs). Superman then reveals he did a fifth feat in Gotham, so the cities will share the convention.
World's Finest Comics 100
Luthor invents a device allowing him to shrink to tiny size, and gets Superman to bring him to the Fortress of Solitude, wherein Luthor gets into the bottle city of Kandor. Superman pursues, but gets captured by Luthor and his gang of Kandorians, as Superman has no powers. Batman and Robin arrive at the Fortress, and go into the bottle city, freeing Superman, but Luthor flees Kandor. The heroes follow, with Superman's powers returning but neither Batman nor Superman can enlarge as their belts were broken....so they have to capture Luthor (eventually fixing their size problem).
This is just one of many times the World's Finest team faces Luthor!
World's Finest Comics 89Justice League of America).
An international gathering of heroes is forming a club under the watchful eye of rich philanthropist, John Mayhew, and is to include Superman, Batman, and the Legionary (from Italy), the Musketeer (from France), the Gaucho (from South America) and the Knight and the Squire (from England; all of whom had previously appeared in Detective Comics #215). Superman's membership to this group is held up as he keeps failing in his missions, which get accomplished by an unknown hero, Lightning Man. Batman investigates, thinking Lightning Man is behind Superman's problems, but instead finds Superman is the problem (thanks to a rogue orbiting Kryptonite meteor, which causes Superman to assume the identity of Lightning Man). Mystery solved, and the end of Lightning Man (and Superman's problems.
in and out of issues of World's Finest Comics!