If both the speaker and X are men:
X is a fellow alumnus of Wabash College.
X and I are alumni of Wabash College.
If both the speaker and Y are women:
Y is a fellow alumna of Wellesley.
Y and I are alumnæ of Wellesley.
Gender neutral, or mixed gender:
Z is a fellow alum of South Torrance University.
Z and I are alumni of South Torrance University.
Z and I both graduated from South Torrance University.
None of these examples state the level of the degree (Associate's, Bachelor's, Master's, Doctorate, etc.) In many cases, that can be guessed from the name of the institution. For example, a "Junior College" degree is probably an "Associate's" degree; a medical school degree is probably a professional doctorate, such as an MD or DDS.