Leader-Hulk is a somewhat obscure character that only appeared in one panel at the end of in a story from "What If?" (Vol. 2) #53 where the Leader. The black tank top the Leader-Hulk wears to similar to what the smart Professor Hulk often wore in the comics, but with black pants and a red belt unlike Professor Hulk's tan pants and black belt. When the Leader's orange jumpsuit started to rip when he started siphoning the Hulk's strength is actually close to what he wore in his comic appearance.
This episode is loosely inspired by "The Incredible Hulk" (Vol. 1) #316-318 by John Byrne. To make the story more Hulk centric, Doc Samson aiding The Avengers to contain the rampaging mindless Hulk is completely removed from the story. Instead the Hulk fights the Leader's Gamma Warriors and Doc Samson is marking time in the stock aid for releasing the Hulk.