shouldCreateGladiatorWithDefaultInitiative I am getting this test case failed I am not sure what mistake am doing could anybody give some hint ?

The kata is suspectible to modifying input objects, e.g fightBetweenSameGladiatorsShouldReturnFirstParameterAsWinner will fail at second test if input is modified (which seems to be expected).

The fight method is a duplicate - here is a similar kata with a slightly different algorithm, but I think I've solved 1 or 2 more katas which were closer to what we're supposed to do here (edit: another similar kata's been mentioned in this comment). As for everything else (implement a constructor and other pointless boilerplate) - that's been done in numerous katas in some form too. As a result, I'd say that this one lacks novelty overall.