Zuko may be a good guy by the end of the show, but he was sneaky and ambitious before that. And despite him being brave enough to fight both his father and sister, he’s much more of a Slytherin than a Gryffindor.
Toph is one of the most reckless and brave characters in all of Avatar: The Last Airbender. But it works for her. Despite her disability, she makes the most of her life and doesn’t let anything get her down or hold her back.