Just as every pastor and pastor's wife are different, every parish is unique, with its own expectations as to what the wife's role should be. Some pastors and their wives work well as a team, with the wives assisting in their husbands' work in whatever way possible. Other couples are more comfortable if the wife has a less active role.
In an ideal situation, the pastor's wife has a role that allows her to willingly use her strengths in such a way that fulfills the needs and expectations of her husband, herself, and the congregation. For example, her talents might include teaching, counseling, organizing, or bookkeeping.
The pastor and his wife should ascertain early on what their parishioners expect from the two of them. If there is any conflict, the pastor should assume a leadership role in communicating and discussing what the best and most suitable decision is for everyone.