Agroup worker who specializes in serving relatively well-functioning individuals who need to learn a specific set of skills (e. g., anger management skills) is likely to form

A psychoeducational group

Explanation:

A psychoeducational group is a kind of group therapy based on cognitive behavior therapy that is involved with educating individuals on how to deal with disorders or more or less cope with it such as the example above. Individuals that share same disorder gather together to be asked questions that concern their diagnosis and are educated in this process. It is usually led by one person who is specialised or a professional in the field.