Pip and Mrs. Pocket are alike in two ways, I believe. First of all, they are both naive to the point of being “clueless” and second of all, they are both not happy with their social status.
Pip is clueless about his benefactor. He immediately assumes it is Miss Havisham, even though he realizes early on what type of twisted woman she is. He ignores logic and persists in thinking that it is she that has provided for him. Granted, there are some reasons for him to think this, but he continues to ignore all evidence to the contrary as the novel progresses. This is why meeting up again with his real benefactor, Magwitch, is such a shock to him. Pip has a false sense of reality.
Mrs. Pocket is also clueless and has a false sense of reality, only much worse than Pip. I have always imagined that Dickens included her character as a foil to Pip – in showing how outrageous Mrs. Pocket was, perhaps he was pointing out, to a lesser degree, the danger of Pip continuing on his own path of distorted reality. Mrs. Pocket is so caught up in the false idea that she is royalty, that she is totally ridiculous and cannot even function in life. She is a baby machine, and that is all. Her servants and her husband take care of the household and the children.
Neither Mrs. Pocket nor Pip are happy with their stations in life. When Pip learns that he is a low-class “blacksmith’s boy” at Miss Havisham’s Satis House, he is no longer satisfied with his own station in life. Prior to this time, he was content living with Joe, albeit perhaps not his sister. He was expected to be apprenticed to Joe when he became of age, and he was OK with that. He figured that perhaps he would not like being a blacksmith, but he loved Joe so much, he thought he would adapt. All of that changed when he saw Estella, became enamored of her even as a young boy, and nothing would ever be the same. He knew he could never have her unless he had greater expectations in life than being a blacksmith.
Mrs. Pocket is in denial about her station in life. In contrast to Pip, however, hers reaches the point of ridiculousness and Dickens uses this to underscore his theme of class struggle. She fancies herself an aristocrat and even though she is not, she acts like she is. This renders her totally useless as a wife and mother. Her children are in chaos about her, as is her household, and all she does is read books about nobility. She misinterprets everything that happens, including almost poking her baby’s eye out and not becoming angry at the cook when the cook gets drunk and passes out on the kitchen floor. Mrs. Pocket gets angry, instead, at the servant who brings the news.
Dickens uses both of these characters to point out his theme about class. The poor characters are the noble ones (Joe, Magwitch, Biddy), the rich ones are evil (Miss Havisham, Bentley Drummle, Estella) or ridiculous (Mrs. Pocket, Uncle Pumblechook).