I have a cavalier 4 / bard 1 / battle herald 6 with leadership feat, then I take the Griffon as a cohort/mount.
The question is: the cavalier have the specials "mount" and "expert trainer", can I apply these on the Grifon, since it will become his mount? The feat "horse master" will apply too?
The same creature can't be both a cohort and an animal companion. It's either too stupid to be a cohort or too smart to be a companion, if I recall correctly.