How did King Boo get out of the portrait?

Answer 1

King Boo was never IN a portrait to begin with. Here is the full sory, from Super Mario Wiki (All credit goes to the good folks there): The Capture of BoolossusPrior to the events of Luigi's Mansion, the ghost hunter Professor E. Gadd managed to capture Boolossus, one of the biggest and strongest Boos in King Boo's forces. Of course, this greatly angered the Boo leader, and the ghost orchestrated a rescue attempt. Professor E. Gadd had brought Boolossus to his lab in Boo Woods. Using a special device called a Portrificationizer, E. Gadd sealed Boolossus in a portrait and hung the new piece of art in his Gallery. Eventually, King Boo and his forces attacked the laboratory. The Boos reversed the settings of the Portificationizer and released Boolossus from his portrait prison. King Boo, in an act of revenge, then ordered that all the ghosts that E. Gadd had captured in his travels should be freed as well. After releasing all of the portrait ghosts and reversing years and years of E. Gadd's work, King Boo magically created a huge mansion out of thin air, and placed it right next to the professor's lab. The Boo leader, his Boo minions, and the portrait ghosts recently freed from their prisons, decided to inhabit the mansion. With a new place to haunt and an army of new ghosts courtesy of released portrait ghost Vincent Van Gore, King Boo decided to enact a new scheme. With his newfound resources, King Boo created a plan of revenge against old rivals of the Boos. King Boo devised a plan to capture both Mario and Luigi, the defenders of the Mushroom Kingdom. The Mansion Hoping to recapture Luigi, King Boo sent the plumber a letter. The message stated that Luigi had won a mansion in a contest and provided the location of the prize. Of course, Luigi was skeptical of such a reward, as he did not recall entering any contest; however, he was excited nonetheless. He asked his brother Mario to investigate the mansion, and said he would arrive shortly thereafter. As such, Mario, along with a few Toads, ventured to the mansion. Unfortunately, Mario was instantly overwhelmed by King Boo's forces and was captured. King Boo then imprisoned the great hero of the Mushroom Kingdom in a portrait, just like the Boo leader's minion Boolossus was previously. The imprisoned Mario was placed in the Secret Altar in the basement of the mansion. Of course, King Boo wished to add another painting to his collection: the portrait of Luigi. The Poltergust 3000While waiting for the arrival of Luigi, King Boo and his Boo minions decided to rest behind a secret door in the floor of the Storage Room. When Luigi arrived in the room, and revealed the secret door, the Boos sprang out from the floor, enraged after being awakened from their slumber. However, the Boos (including King Boo) broke off their surprise attack when they noticed the Poltergust 3000 on Luigi's back. The special ghost-capturing weapon was previously given to Luigi by Professor E. Gadd, who wanted the plumber to recapture the portrait ghosts. The Poltergust 3000 was one of the few things King Boo feared, and he, along with the other Boos, flew off in different directions and hid in the mansion. The Boo leader himself traveled to the Secret Altar in the mansion's basement. While in the protected room, King Boo amused himself by watching Mario's pathetic pleas for help. The Secret AltarThe path to the Secret Altar was locked by a special key in the possession of Vincent Van Gore, who had locked himself in the Artist's Studio on the third floor of the mansion. After capturing the ghost and retrieving the key, Luigi discovered that he needed more than a key to access King Boo's lair. If the green-clad ghost hunter attempted to enter the Secret Altar without catching a certain number of Boos, King Boo himself would materialize before Luigi and blow the plumber away to the Foyer, the entrance of the mansion. However, since King Boo's power was directly related to the number of Boos in the mansion, Luigi could weaken the Boo leader by capturing the Boos hidden in the various rooms. After Luigi captured at least forty of the mansion's fifty Boos, King Boo lost his ability to blow the ghost hunter away from the Secret Altar. As such, with his Poltergust 3000 in hand, Luigi entered King Boo's lair and prepared for a final showdown. The Final Battle Upon entering the altar, Luigi noticed King Boo staring at his most prized possession: the Mario painting. However, King Boo turned to Luigi and stated his desire to complete his set and add a Luigi painting to the collection. After saying this, King Boo flew into the Mario painting hanging on the wall. Strangely, the figure of Mario transformed into the form of Bowser, and the new Bowser painting inhaled Luigi into the canvas. After entering the painting, Luigi was transported into a strange arena that resembled the mansion's roof. The green-clad hero was in for an even bigger shock when none other than the colossal form of Bowser appeared before him. It is unknown what happened to Mario, but he was probably pushed farther back in the painting. In reality, King Boo was inside the hulking beast, secretly controlling the Bowser suit from Behind the Scenes. King Boo used this Bowser disguise to attack the heroic Luigi, shooting flames at the green-clad plumber, and even attempting to inhale Luigi into his mouth. The beast also possessed tha ability to create three large spiked bombs out of thin air, and toss the explosives at Luigi. The hero knew he had to fight back, and used his Poltergust 3000 to pull in one of the spiked explosives and release it into the beast's mouth. The result of this attack blasted off the head of the Bowser costume, knocking King Boo out of Bowser's body. Exposed to the power of the Poltergust 3000, Luigi began to deplete the ghost's five hundred hit points. Unfortunately, Bowser's head would hover around the arena and shoot ice blasts at Luigi. If frozen, Luigi could shake himself free from the icy prison. He would have to quick, as he took damage every second he was frozen. Eventually, King Boo would fly back into the dormant Bowser body and the head would reattach itself. Resuming the fight. Luigi repeated the same process, slowly weakening the ghost, but after King Boo's life fell below two hundred HP, the head of the costume would reattach backwards whenever he returned to the Bowser body, causing the Bowser suit to run around aimlessly, destroying everything in its path. Eventually, the Bowser body would put its head on correctly and resume the fight. After a long and difficult battle, Luigi managed to completely drain King Boo's HP and capture the ghost leader inside the Poltergust 3000. Without the presence of King Boo, the Bowser suit collapsed lifelessly onto the ground. After the battle, Luigi picked up King Boo's crown, worth 5000G (the value of only 10 Gold Coins) and added it to his treasure collection (note that after Luigi's Mansion he has a different crown throughout the Mario series). Upon returning to the mansion, the green-clad ghost hunter also picked up the Mario painting and quickly traveled to Professor E. Gadd's lab. In the lab, Luigi connected the Poltergust to the professor's Portrificationizer, dumping its ghostly contents into the machine. Surprisingly, not only did the spirit of King Boo appear in the Portrificationizer, but what appeared to be the robot Bowser also materialize. With King Boo captured and imprisoned, Professor E. Gadd hung his new portrait in the most elegant room of his gallery. In the end, Mario was finally released from his portrait and Luigi emerged from his adventure a true hero.