Ramona Fradon and Robert Allen Smith gave us the cover of Super Friends #28 (January, 1980) which teased a confrontation among DC's top heroes and most villainous monsters (but they were only magically transformed guests).
Here, a look at when these monsters first appeared, and when they met who they faced!
BizarroBizarro version of Superman appeared in Action Comics #254 (July, 1959) by Otto Binder and Al Plastino as an imperfect duplicate of Superman created by Luthor, but, Superboy had faced an earlier Bizarro back in Superboy #68 (October, 1958), though that version was destroyed.
DemonCamelot to fight evil. He first met Wonder Woman in Wonder Woman #280 (June, 1981).
Man-BatMan-Bat in Detective Comics #400 (June, 1970) by Frank Robbins, Neal Adams and Dick Giordano. While Batman and Man-Bat faced off in that issue, Robin didn't meet Man-Bat until Power Records 30 in 1976 in the aptly titled "Robin Meets Man-Bat".
Solomon GrundySolomon Grundy first appeared in All-American Comics #61 (October, 1944) by Alfred Bester and Paul Reinman fighting the Golden Age Green Lantern as the animated corpse of Cyrus Gold, but, even with multiple encounters with the JLA...never really ran into Aquaman before the Crisis On Infinite Earths.
How's that for a tricky treat?