Click green flag.
I beat Luigi's Mansion 3! How I did it was once King Boo multiplied into 3 I waited till they each threw 1, not 3 bombs while avoiding his other traps. Then I made sure to shoot it at the correct one and if I did, King Boo went back into one piece and fell to the ground. I sucked up his tongue and then slammed him. And then he died! How to get past King Boo as one: The tongue: King Boo will throw his tongue at you three times. Avoid those and then he will try to trip you. Jump as soon as he starts. Lightening: King Boo will have lightening. When he does, go on the blue spots. Fireballs: King Boo will shoot fireballs at you, avoid him and stay aware. Bombs: King Boo has bombs, when he shoots them, avoid them and then quickly run to the ones that are not blinking with red. Suck them up and then shoot them at his mouth. He will explode and then pass out. Run to his tongue and suck that up. Bring out Gooigi and have him suck up his tongue as well, then slam him. King Boo second round: King Boo will multiply into two, here is how to avoid him: Bombs: Same thing as last time. Lightening: Same thing as last time. Jumps: The two King Boos will go into the air. You will see their shadow. Avoid them and jump when the second King boo comes down. Fireballs: Same thing