When it comes to describing someone's poor writing skills, there are numerous synonyms available to choose from. Some common terms that can be used in place of "writes badly" include "scribbles poorly," "pens poorly," "drafts poorly," "composes poorly," "formulates poorly," "penmanship is poor," or "lacks writing proficiency." Additionally, you could use more descriptive terms to convey the degree of deficiency in writing, such as "penmanship is illegible," "script is indecipherable," "composition is incoherent," or "writing skills are subpar." Ultimately, there are many ways to express that someone has weak writing skills, and the specific choice of language will depend on the context and intended tone of the message.