Battle of the Orcs on the Frozen Throne: The Establishment of Dolock. At the first level, when Reksa and Lokhan help Draktar with his task, they will meet a panda. Panda wants to make wine, and wants Reksa to find materials. Some want to kill Qinglong, and some are in the orc market. When it's finished, the panda is yours.
In the fourth pass of the night elf campaign, protect the messenger to do the task. Ma Wei can meet the panda of 1 in the lower left corner. Blink your eyes and the panda will disappear. And left agile +3 boots.
Pandas also appeared in the third level of the Battle of the Blood Elves.
I can't remember the rest.