Successfully complete story mode with Soiree and Alba to unlock Duke.
Successfully complete a challenge in challenge mode to unlock alternate costumes.
Successfully complete the game with any character to unlock that character in the profile screen. Note: You can now also select their rigging model in their profile and use it during the game.
Successfully complete all challenge mode missions to unlock the Cemetery stage.
Successfully complete 25 challenge mode missions to unlock the Esaka stage.
Successfully complete 25 challenge mode missions to unlock the Infernal Gate stage.
Successfully complete 10 challenge mode missions to unlock the Show Time stage.
To get 30 hits in one of the challenge mode missions, use Ryo's Whipslash Bash with a Light Punch then use his level 2 special.
Fighting Duke with Mai can be hard. However, if you keep using her combos, such as Super Deadly Ninja Bees and Windwill Waster and do not allow Duke to power up any of his most devastating attacks, you will defeat him. Note: This may require a lot of practice; use practice mode until you are skilled with Mai's combos. Defeating Duke in story mode will unlock Mai's profile and rigging model.
At the beginning of Duke's fight on the normal difficulty setting, sidestep as soon as the fight begins to avoid his first attack, then attack him, preferable knocking him to the ground. After he has been knocked to the ground, try to stay in the center of the ring. Duke may do the following when you fight him:
He may walk up to you and use one of his infinite power gauge attacks. In one of these, he is not able to take damage when getting ready to use the attack and you must block the attack, which will crush your guard. He may then use it again up to three or more times then go into a combo. Duke will use a power gauge and probably attack you with a combo or crouch and kick you to the ground. To have a chance against this, block his powerful attack. He may use it repeatedly, but keep blocking it. If he attacks with a different power gauge attack, also block it. As soon as he comes at you with a combo, sidestep and attack him.
If he uses a power gauge attack and hits you with a flame that goes across the ring, it will knock you to the ground, then he will do any of the above actions. Block it and wait for him to come at you with a combo.
If he crouch's and kick's you and knocks you to the ground, then use multiple combos to drain about half of your life then put you against the wall. Sidestep his crouch kick and wait for him to come at you with a combo. When he starts the combo, sidestep and attack him. Duke may crouch and kick several times before he attacks with a combo or power gauge attack; do not get excited and attack him before he is ready to use a combo on you. If you sidestep too late or too soon, Duke will turn and hit you with every blow. When you sidestep, wait about half second before you attack. If you attack too soon, you will not have turned enough and will attack in a different direction that Duke has gone. If you attack too late, Duke will turn around and block the attack and counter with his own attacks.
If he walk's up to you and try to use a combo, sidestep and attack him.
If he walk's or run's up to you and then kick you twice, this will knock you across the ring to a wall, and he will use a combo mixed with power gauge attacks. To avoid him taking most of your life, roll backwards before he kicks then wait for him to come at you with a combo, then sidestep and attack.
If he stomp's to knock you to the ground, then uses any of the above actions -- block it and wait for a combo to be used.
If you pin Duke against the wall or stay near him for a certain amount of time, he will knock you into the air and do any of the above actions. You cannot hurt Duke when he does this. Keep your distance unless he comes towards you.
If he walks into you and either does a grab and throw, and steps on you or does a combo, then sidestep him. If he attacked with a combo, you are in a perfect position for an attack. If he went for a grab, you may have avoided it, or he will get you and stomp you into the air. There is not a sure to tell which method he is going to use, but he goes into a combo most of the time.
If he runs at you and does any of the above actions, the only thing that you can do is hope that you sidestep or roll at the correct time. Occasionally Duke will do something that is not described above but is not done often enough to worry about. You can use any character, and as long as you know at least two combos for that fighter, including one that knocks an opponent to the ground. This requires some practice to know when to sidestep, block, and attack. However when you learn this, Duke can be defeated without much of a problem.