I appreciate the time you put into creating your post, Niente. That said, I think the way you open your assertions with the third question here is problematic:
Pet battles? Why? Who wanted this?
Critters break out of crowd control effects more quickly. Beasts
Beasts deal 25% extra damage below half health. Humanoid
Humanoids recover 2% of their maximum health every time they attack. Dragonkin
Deals 50% additional damage to targets with less than 25% health. Flying
Flying creatures gain 50% extra speed while above 50% health. Aquatic
The duration of harmful damage over time effects is reduced on Aquatic pets. Elemental
Elementals ignore all weather effects. Undead
Undead pets return to life for one round when killed. Magical
Magic pets cannot be dealt more than 50% of their maximum health in one attack. Mechanical
Comes back to life once per battle, returning to 25% health.