I suggest watching a fighting videos in boxing, kickboxing, and mix martial arts to give you some ideas about creating an animations. This shouldn’t take you forever it’s just creating animation on Blender I have done it with my basic knowledge of Maya.
Here’s my suggestion your free to discard my thought. I was thinking of creating four types of animations fighting mode, defense mode, “damage mode”, and “tired mode” there’s a quotation because I’m making this up as I go on. In fighting mode the player is in a fighting stances ready for punch, kick, etc… or any strikes and if the opposing player makes the first strike this should signal the other player’s defending mode to be triggered and wait for defense button to be press to make that defense animation work. Then there’s the damage mode and tired mode let’s give these thing for the health bar and stamina bar just like life in real like people get tired maybe something like panting, heavy breathing, chest pumping faster, etc… is all part of the “tired mode” the same goes to “damage mode” where players if get hit in certain parts of the body would touch it or stuff what people would do when they get hurt.
That’s my best suggestion how to tackle this solution.