Alright, I have some reports for you already.
At the SeeD examination, Xu is called forth to explain the scenario occurring in Dollet to Seifer, Zell, and Squall; all members of Squad B. Quistis is also present. Although she does not take part in the mission, Xu was vital in the plan. Later, when NORG tries to take over the Garden, Xu aligns with and supports Headmaster Cid, even threatening Squall's party when they, unaware of what's going on, run into her and do not identify themselves as aligned with Cid.
When Balamb Garden becomes mobile and Squall is given the rank of Commander, Xu, along with Quistis and Nida, can be found at the Command Bridge, helping Squall by keeping things in order. During the Battle of the Gardens, Xu coordinates Balamb Garden's defense and offense. In the party celebrating SeeD's victory over Ultimecia, Xu appears on Irvine's recording of the event and waves to him.
She unwittingly survives the time compression along with the other CC group members by boarding the Ragnarok and can be challenged to Triple Triad on disc 4 by finding the airship on the Kashkabald Desert.
Xú (徐) is a Chinese surname meaning "gently". It is rendered in pinyin in this case, as its on'yomi reading would have been "Jo".
Xu is called Shou in the German version, and Shu in the French, Italian, and Spanish version.