Happy Halloween, Scooby-Doo! does not include any explicit or implicit LGBTQ+ characters or themes. The narrative focuses solely on the mystery-solving adventures of the Scooby Gang without addressing aspects of queer identity or relationships.

The film "Happy Halloween, Scooby-Doo!" does not feature any identifiable transsexual characters or themes. The narrative focuses on the Mystery Inc. gang, Batman, and other characters solving a Halloween-themed mystery, without any elements related to transgender identity.

The movie does not contain any action or adventure elements.

The film features the established Scooby-Doo characters and guest stars like Elvira, Bill Nye, and Steve Urkel, all of whom maintain their canonically established genders from previous appearances or real-world history. No legacy characters are portrayed with a different gender.

The film features the classic Scooby-Doo characters, Fred, Daphne, Velma, and Shaggy, who are consistently depicted as white, aligning with their long-established canonical portrayals. No established characters from the Scooby-Doo franchise or other legacy characters appearing in the film undergo a race swap.