About the name of suggested reveiwer I am going to submit a short math paper to a journal. During the process of submission I am asked to suggest the Editor \ Reviewers. In this respect, can I write the name of my co-advisor of my Ph.D as a potential reviewer? Need to say, we have a joint paper with my co-advisor.
Recent joint papers are one of the first examples of conflict of interest most journals mention, see for example here and here. Being your advisor is also explicitly mentioned as a conflict. I would avoid suggesting this person as a potential reviewer, this will at the very least raise eyebrows unless you have a very convincing reason.