The animated short film "Sledgehammer O'Possum - What's Going on Back There?" does not feature any identifiable LGBTQ+ characters or themes. Its narrative focuses on slapstick humor and cartoon violence involving animal characters, with no elements related to queer identity.

Based on the information provided, there are no identifiable transsexual characters or themes present in the film. Therefore, an evaluation of its portrayal is not applicable.

The movie does not contain any action or adventure elements.

No prior source material or established characters are provided for "Sledgehammer O'Possum - What's Going on Back There?". Without a pre-existing canon, no character can be identified as having their gender changed from an earlier, established portrayal.

The film is an animated short featuring anthropomorphic animal characters. The concept of human racial identity and subsequent race swaps, as defined, does not apply to its cast.