* ガキ (gaki): This is a common and generally neutral term for a child, but it can be used derisively to refer to a mischievous or unruly child, similar to "brat" or "kid." It's more about the child's behavior than their inherent nastiness.
* 生意気な子 (namaiki na ko): This translates to "impolite child" or "cheeky child." This emphasizes the brat's disrespectful attitude.
* 生意気なガキ (namaiki na gaki): This combines the two above, emphasizing both the child's age and their bad manners.
* 小僧 (kozō): This literally means "young boy," but it can also be used to refer to a mischievous or troublesome boy, especially in a slightly older context than "gaki."
* いたずらっ子 (itazurakko): This means "mischievous child," focusing on their playful but annoying behavior rather than outright rudeness.
The best choice depends on the context. For a generally negative but not overly harsh connotation, ガキ (gaki) is a good starting point. If you want to emphasize rudeness, 生意気な子 (namaiki na ko) or 生意気なガキ (namaiki na gaki) are better choices.