Synagogue Services Appropriate for a Bar/Bat Mitzvah
If you haven’t done the advance work, don’t panic. Just about any service when the Torah is read is appropriate for a bar mitzvah. Shabbat morning is the most common choice; the Torah is always read at this service. The Torah is read on Monday and Thursday mornings too. Special Torah readings are set for Rosh Chodesh, the beginning of each Jewish month, all of Chanukah, Passover, Sukkot, and Shavuout. Rosh Hashannah and Yom Kippur feature Torah readings as well.

Certain readings carry special obligations and generally will not be offered to bar mitzvah boys. These included the maftir of Parshat Zachor, Parshat Parah, the reading on the seventh day of Pesach, on Shavuout, or on Shabbat Shuva. (Kitov, 228)

What a Bar/Bat Mitzvah Needs to Know
In the past, the bar mitzvah celebration was marked by thirteen year old boy beginning his life long commitment of donning teffilin each weekday morning and Aliya during the reading of the weekly portion at the synagogue on the first Shabbat after the thirteenth birthday.  But these days a young man turning thirteen often partakes in many of the synagogue rituals.  Though there is no ritual that must be done to be considered an adult Jew in the eyes of halacha, any combination of the following ceremonial services. An undertaking dependent on the synagogue’s expectations and the bar mitzvah boy’s wishes. (The orthodox Bat Mitzvah girl does not participate in the synagogue prayer rituals.)