wolves and other animals are not that hard to create, just put an extra cpu player that would control an "animal faction" with just the animal and one "building", that would be a cave that would generate animals from time to time, the thing would be how to control the creation rate, maybe give this animal faction 1 food (or whatever resource) per second and charge X food to create one animal (X would be the amount of seconds to create animals).
Of course this faction would be hidden, so normal players can't control it.
And of course it would be editable as other factions
as for making it goes against everyone, just put it as team 5 or any other team number that no other player would be