Upon arriving at the hotel, Weepy and his siblings immediately cause all sorts of mischief, including attacking the zombie bellhops, jumping on a piano keyboard, playing in the sand that Murray leaves behind, and even urinating on the furniture before their messes are cleaned up by the witch housemaids. They are often seen in groups, and appear to be quite violent and undisciplined for the most part. It is even mentioned by Wanda that "the kids threw the mini-bar out the window!"
The pups mostly bark and growl, but are shown to be capable of speaking English, as one pup apologizes for misbehaving and chewing on Dracula's cape.
The pups are seen in several locations throughout the film; in one instance, Drac uses their rambunctiousness to get even with Griffin by tricking him into holding a piece of bacon, which causes a pack of the pups to attack him. In another, a group of 10+ pups is seen with Wayne chewing on and attacking zombie Mozart before the werewolves are scolded by Dracula.
They are later seen in the auditorium, chewing on a skeleton out of boredom before they see Johnny go by on his scooter. They then a take turn on his scooter as Winnie runs after them.
A group of pups are also shown swimming the pool, and laughing as they watch Wayne pull Griffin's pants down.
Before Wayne receives a wake-up call, he is surrounded by his children, preventing him from getting proper rest by sleeping on top of him. They soon wake up and react to the sound of the alarm clock going off by howling; The pups fall off of Wayne as he gets up. Later that day they are seen at Mavis's birthday party, dancing on a floating table before Winnie pushes them off.
Their largest role in the film is when they are called by Wayne to help him track down Johnny. They don't listen, however, and they wreak havoc and roughhouse instead. Wayne tries to get them to get the scent of a shirt that Johnny dropped, but they sniff his rear end instead. When Dracula suggests that none of the pups respect him, Wayne eventually calls for Winnie, who was able to tell them that Johnny has boarded a plane that will be leaving soon. The pups leave when Dracula tells them to "go back to their mother."
Lastly, they are seen licking Quasimodo, who was frozen by Dracula.
Hotel Transylvania 2
Attending a birthday party for six of them, Dennis wishes a happy birthday to pups named Wally, Wilson, Whoopty, Wade, Weepy and Wanye. They get into the candy from the piñata Mavis broke, and go on a sugar-fueled rampage. Their antics cause Dennis to get hurt and have one of his teeth knocked out.