@Neji
It wouldn't be fun if all the details of the new mounts are already posted here...
The real problem about creating new mounts is variety. Otherwise it will just be another mount will slightly different bonuses and dmg calculation.
What else can be done besides setting mount to attack or heal, how much atk/def (etc) buff the player gets, the cost (purchase & maintain)?
Unlike the mobs in the forest, you can't enter codes that would give mounts special attacks/actions, correct?