Oners is a slang term used to refer to individuals who cause difficulties or are difficult to deal with. In business settings, oners can be clients who demand too much or employees who are constantly causing problems. There are several synonyms that can be used in place of oners, such as troublemakers, nuisances, headaches, challenges, and burdens. Other similar words to oners can include irritants, pests, obstacles, or even difficult individuals. However, it's important to be mindful of the context in which these words are used and to avoid offending anyone. As with any word, context is key, so use them thoughtfully and judiciously.