You manage them in the way you manage everyone else.
You should know what is expected of every employee including how they code, how they interact with others, how productive they are, what quality you expect and you hold them to it firstly in the job description, then in 1-to-1s and maybe, eventually in the exit interview.
A business is about creating benefit to the employees, the shareholders and the customers. Whether somebody is "smart" or not is irrelevant, they are either contributing or they are not.
You should know what is expected of every employee including how they code, how they interact with others, how productive they are, what quality you expect and you hold them to it firstly in the job description, then in 1-to-1s and maybe, eventually in the exit interview.
A business is about creating benefit to the employees, the shareholders and the customers. Whether somebody is "smart" or not is irrelevant, they are either contributing or they are not.