Casper's Haunted Christmas (2000) on Netflix

Plot summary

The rule is that Casper must deliberately frighten at least one person before Christmas Day; the fright humans feel just from seeing him does not count. If Casper fails, Kibosh, the ruler of all ghosts, threatens to send the Ghostly Trio to a void called the Dark, and he takes away their haunting licenses before flinging them to Kriss, Massachusetts. There Casper meets the Jollimore family, and his kind nature takes over: he becomes friends with the Jollimores' daughter Holly. The Trio, fed up with his good behavior, secretly call in Casper's look-alike cousin Spooky, who arrives with his girlfriend Poil, to handle the scaring.