You need 200 wins in ONE of the GCs for the ADS mount. It's not like the commanders coat achievement which counts wins from every GC. Even though these achievements are worded the same.

Read:

http://forum.square-enix.com/ffxiv/t...he-Enemy-Lines (A dev replied to this thread)

and read

http://forum.square-enix.com/ffxiv/t...56#post3310556