It is a monster that inhabits Monstropolis, like all other existing monsters. He is over two meters tall and has blue hair with purple spots, and he is the one who has the record of scaring children. He lives quietly with his best friend Mike Wazowski, until one day, while looking for some reports from Mike, Sulley discovers that one of the doors of the human world was left open. Approaching to close it, he discovers that a girl has entered Monstropolis, and this is harmful to all monsters (since they believe that children are toxic and therefore fear them). Mike and Sulley hide Boo (that's what they call her because when Sulley found her, she scared him with a Boo!) While they search for her door, to take her back to the human world. But none of this is easy, as Randall, Sulley's rival, annoys him in everything he does and tries to hurt him. Throughout the entire adventure, Boo has a lot of affection for Sulley, even though she is a monster. summarize this for me please