I have some old info about my former PP'd greater hiryu.
Farmed for a greater hiryu when Tokuno first opened with near best stats as well as 120 wrestle pre tame. Anyhow it was not until after 2009 stygian expansion that I decided to max all of the skills. During the training it ended up dying & noticed the wrestle .1 wouldn't regain after 10+ hrs sparring on a shadow ele. Friend told me if you took it down to 100 points from res killing, then released & re-tamed, it should then start to regain to cap again. NOPE, the wrestle still remained at 100 points, & wouldn't increase, SIGH. Now, having been 4 years later, I'm not sure whether or not PP'd hiryus can now regain their melee skills after resing one with above 100 points. If you do happen to obtain a PP'd one, just to be safe try to be extra careful about the pet dying until you find out.