User blog comment:Lord Loss/Monster Appreciation Day: Tigrex/@comment-203.206.107.128-20111218122601/@comment-180.3.255.9-20111218123722

The full quest listing is already out on jp wikis and Tiggy aint in there. So unless Tigrex is DLC which they never add new mobs as DLC, you can count him out of 3G.