Thanks! :D I'm thinking of making an arcade mode, with different rooms with player AI using different settings (Wouldn't be like the old singleplayer I was trying to do, would be more akin to Super Smash Bros singleplayer). So I can reintroduce the boss in that mode XD I really enjoyed making him.
The letters on his fists says "Uncle Knuckle", each time you successfully hit him he loses a letter on his fists. When he loses all his letters he dies.