Here are the official write-ups for this contest:
Captain Boomerang
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First appearance: Flash (vol. 1) #117 (Dec. 1960)
Created by: John Broome and Carmine Infantino
Powers and abilities: Captain Boomerang is an unparalleled master of throwing boomerangs, and employs a number of trick boomerangs including razor sharp boomerangs, sonic boomerangs, exploding boomerangs, and remote controlled boomerangs. He has also been known to use giant remote controlled boomerangs as vehicles, traps, and weapons.
VS.
Kraven the Hunter
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First appearance: Amazing Spider-Man (vol. 1) #15 (Aug. 1964)
Created by: Stan Lee and Steve Ditko
Powers and abilities: Kraven is an expert hunter and tracker, and a master of numerous weapons and martial arts. Further, he has enhanced strength, speed, senses, stamina, and reflexes from an herbal potion which he ritualistically ingests. He uses numerous weapons in combat, most often spears, nets, axes, and knives, as well as various toxins and tranquilizers.
Now, right off the bat, you may think that Kraven has an advantage, but bear in mind two things: Captain Boomerang has the advantage when it comes to range, and Kraven's enhanced physicality does not propel him to a superhuman level. He's more akin to Captain America's level of strength, speed, etc.
I think it's gonna be a good fight!