Before it can be ridden in combat, a griffon requires practice bearing the weight of its rider. In order to be trained successfully, a griffon must first be helpful toward its trainer (possibly requiring a Diplomacy, Intimidate, or Handle Animal check). After that, 6 weeks of practice and a successful DC 20 Handle Animal check is sufficient for the beast to be comfortable with its burden, and due to their intelligence, trained griffons can be treated as knowing every trick listed in the Handle Animal skill description, possibly even responding to new, simple requests made in Common.