The breedable game mechanic allows mobs of the same species to breed with each other to make new baby mobs. For most mob all takes is to feed two and they will enter love mode (emit heart particles), shortly after they will produce a smaller baby mob. If a mob is tameable, it must be tamed before it will enter love mode.
NBT Tags, entity data fields for mobs that can breed
There are special tags that relate to breeding and if a mob is a baby, checkout the summon mob generator for tag usage.
Can I breed mules in Minecraft?
No, Mules are not in this list, as they can not reproduce (as in real life).
Can I breed zombie mobs?
No, Zombies, Husks, Drowned and Zombie Pigmen are not breedable. The baby versions use a special NBT entity tag "IsBaby" to toggle baby version. See the zombie summon mob generator for tag usage.
How many breedable mobs are there in Minecraft
20 mobs according to our database selection.