I have just come to the realization that Mules would be unobtainable with Animania's default Vanilla Replacement functionality. Whilst this isn't a huge deal I feel that this 'breaks' a vanilla mechanic and hope to see Mules obtainable without having to resort to having both Draft Horses and Vanilla horses available.

Vanilla Mechanic
Obtaining a Mule is done by crossbreeding a Horse and a Donkey

Version
I'm on 1.12.2, but this would of course affect versions right back to when Stallions were introduced I'd imagine.

You are correct. I can actually check if they're donkeys or mules and not remove. Can add.

Actually, I'm not sure that'd work.

Having disabled all mobs from spawning except Draft, horse, donkey and mule, I can see that Donkey's do in fact spawn. The problem is that there are no Vanilla Horses to breed with Donkeys to create Mules. Mules do not spawn naturally in Vanilla MC, they must be bred from a Donkey and a Vanilla horse.

I'm not sure how difficult, or even if it is possible to allow the Stallions to breed with Donkeys to create the Mules, If that isn't doable or is far to much effort, perhaps adding Mules to Animania's Natural Spawn config would be a solution to having them at least obtainable out of the box?