You may ask, 'What happened to them?' Okay, I'll tell you about some of it (beware of amusing content)
Mario
Mario tried to find the exit when he saw a path with lots of spaghetti. Of course, he followed the path and got trapped in the cage.
Luigi
When Luigi was finding the exit, he noticed that some Boos were following him. He ran and ran but ended up in a dead end. The Boos, then, trapped him in a cage.
Bob and Boopkins
After some discussion, Bob and Boopkins decided to stick with each other. Boopkins walked and walked until he noticed Bob was gone. Of course, he went back to find Bob, and saw the Garo trapped in a cage. Boopkins tried to rescue him but he failed and ended up getting caught.
Meggy
Meggy saw a paper on the floor, saying, 'The Exit is at the true inside core in the mansion.' She picked up the paper and continued to find the exit. 'At the true inside core? What can it be?' she thought. 'Come here Meggy, I'll tell you.' said a voice. It was Desti. Meggy simply followed the ghost but she ended up trapped in a cage.
'Hey Meggy! It's me Desti!' said a voice inside Meggy's head. 'You were tricked.' 'How? I followed you and got trapped!' said Meggy, angrily. 'Calm down, Meggy.' said the voice. 'Trust me every single word.'
'To be honest, I am now illusion. Even when I saved you in the subway, when you see me, it's only illusion.' The voice continued, 'Remember, I'm not visible. Now, I'm in your heart. Remember me, and it will be fine.' Then there was only silence. 'Thanks…Desti.' said Meggy. She cut the rope, pinned the paper with her knife and pulled the rope, Morsing 'SOS'.
After receiving the call of help, Saiko and I followed the rope's 'instructions' to find the rest of the crew.