When Fawful absorbed some of the Dark Star's power, he was transformed into Dark Fawful, but was punched away by Bowser before he could finish absorbing the Dark Star. The Dark Star began searching for Dark Fawful. Dark Fawful transformed Peach's Castle into a robot, which fought Giant Bowser and lost. Bowser then tracked down Dark Fawful and fought him. Dark Fawful's Vacuum Helmet was destroyed by the Mario Bros. before Bowser defeated him, and his body was destroyed; however, as he possessed the Dark Star's power, he could not die as long as it remained, and was reduced to a bug form, but was then inhaled by the Dark Star, now in the form of Dark Bowser, who then became complete.
When Bowser was fighting Dark Bowser, every time Bowser defeated his dark clone, Dark Fawful, now combined with the Dark Star Core, would fully heal him from within. When Bowser attacked Dark Bowser's stomach, Dark Fawful and the Dark Star Core would be spit out. Bowser then inhaled them, and Mario and Luigi fought them inside Bowser. They needed to take out Dark Fawful's glasses and eyes before attacking the core. Often Dark Fawful would leave Bowser and return to Dark Bowser. Once the Dark Star Core was defeated, Fawful was seemingly killed, and Bowser was able to destroy Dark Bowser. Fawful reappeared, as a head, and blew himself up in a final attempt to destroy the Mario Bros., which instead sent them and everyone else flying out of Bowser through his mouth.
Bowser vs. Dark FawfulEdit
Dark Fawful has 17,36 HP. He will dodge all of Bowser's attacks, and can only be damaged while swinging back and forth on his vacuum helmet to hit Bowser, in which Bowser can counter by punching him, until he swings counterclockwise, which Bowser must duck to avoid. He also creates four portals. There are two he can throw energy balls into, and the other two are the ones they will come out of to hit Bowser. One is above him and must be countered by ducking, and the other is in front of him, which Bowser must punch the energy balls that appear from it. The portal directly above the one above Bowser is the one that leads to the one above him, while the other portal leads to the one in front of him. As he has more damage, Dark Fawful might switch them around. He also uses a ray gun to shoot an energy beam or two consisting of stars that circle around in front of Bowser. The only way to destroy it and prevent its attack is for Bowser to punch the big star in the ray of stars, which often appears and disappears. The damage Bowser does to Fawful by punching him in counterattack will never defeat him; the Vacuum Helmet heals Dark Fawful.
Eventually Dark Fawful will detach his head from the vacuum helmet. Bowser can then inhale the vacuum helmet for the Mario Bros. to fight. It has 1200 HP. After several turns it will go back to Dark Fawful. Once it is destroyed, Dark Fawful can no longer dodge Bowser's attacks. Dark Fawful can also create several dark energy balls around himself, which Bowser must punch Goombas at or else Dark Fawful will attack for massive damage.
Mario Bros. vs. Dark Star CoreEdit
While Dark Bowser is Bowser's half of the final battle, Dark Fawful and the Dark Star Core together are the Mario Bros. half, and in a sense, Dark Bowser's only weak point, and the thing keeping Bowser from destroying him. Dark Fawful's weak point is the Dark Star Core, but his legs and glasses must be defeated first. The glasses must be attacked first. They each have 250 HP. Once both glasses are taken out, his legs can be attacked. Snack Basket is an efficient way of defeating them, as they have 156 HP each. It is then that the Dark Star Core can be attacked. It has 1,560 HP, which is less than that of Blizzard Midbus. Spin Pipes are a good way of damaging the core.
Dark Fawful attacks by stretching his arms and shooting energy balls through them. These can be countered with hammers. If a big energy ball is hit back at him, the arm will retract. He can also grab the Mario Bros. and have the Dark Star Core shoot energy waves at the Mario Bros. Only if the brother is aligned with the core will he have to jump. Sometimes both have to jump, sometimes neither. Dark Fawful's other attack is to send the Dark Star Core after the Mario Bros while chasing after them, trying to eat them. The core will sail over their heads, either surrounded by red or green energy, indicating which brother it will ram into from the left side. This must be jumped over, and will take some getting used to, as there is a bit of a delay before it attacks at first, but speeds up later. If hit enough, the Mario Bros. will be forced backward into Dark Fawful's mouth and receive a lot of damage. The object is to dodge until the Mario Bros. reach the light.
When the Dark Star Core is vulnerable, it has some attacks of its own. It will create an arrow of dark energy that spins around (slightly similar to the spin attacks of Cackletta and Elder Princess Shroob, but never getting tougher as the core takes more damage) and the Mario Bros. must jump over it after it spins above their heads five times. After that it will shoot an arrow of energy at one of the Mario Bros., who must hit it back at the core with a hammer. Its other attack is to charge up and shoot an energy wave at the Mario Bros., which can only be dodged by grabbing onto Starlow as she circles around them. They have much more time to dodge this than when they fought the Dark Star in its original form.
After two turns of being vulnerable, the Dark Star Core will return with Dark Fawful inside Dark Bowser, and Bowser must defeat him again and inhale Dark Fawful again for the Mario Bros. to damage the Dark Star Core some more. When the Dark Star Core is finally defeated, so is Dark Fawful, and all Bowser has to do is deliver the finishing blows on the now-unstable Dark Bowser.