This can only be done if you set up doa thrashings to be infinite on the menu and it must be done in training.
Use K' as your character and get you oponent close to a wall. Then use the Doa thrashing that has 16 moves Where he throws a something at the oponent(?). Just before he is about to deliver the last move; perform the DOA Thrashing again. Keep repeating this procedure, eventually you will have 99 hits, thats as far as that goes, but you can keep doing it
Duke is the boss in this game. Beat the main mode with Alba and Soiree to unlock him.
Finish some Missions in Challenge Mode.