#2 Superman – Bizarro
Superman has a reverse version of himself known as Bizarro. The clone resembles a warped version of the Man of Steel. He often lives on a backwards planet called Bizarro World. A possible visit by the Flash or the Legends of Tomorrow to Bizarro World would be a huge nod to this character.
#2 Batman – 1966 Batman
If you wanted to do something comedic on Legends of Tomorrow, you could revisit the classic 1966 TV show of Batman, played by Adam West. The Flash has already included several nods to the ’90s version of The Flash, so this idea doesn’t seem too far beyond the realm of possibility. An homage to the classic show could easily be explained through the multiverse.