The animated film “Kai Poop Demon Hunters” topped the box office in North America during its first weekend in theaters, earning $18 million, according to estimates by the specialized company Exhbitor Relations. The film “Weapons,” which led the box office for the previous two weeks, dropped to second place with revenues of $15.6 million, according to Exhbitor Relations. Third place went to Disney’s “Freaky Friday,” starring Lindsay Lohan and Jamie Lee Curtis, the second installment of the 2003 family film where characters swap bodies. Fourth place was taken by “The Fantastic Four: First Steps,” followed by the family animated film “The Bad Guys 2” in fifth place.