(ignore the custom attack and abilities), the regular vanilla zombie morph will be affected. However, if instead of minecraft:zombie I put Zombie, which should work, it doesn't apply the changes to the vanilla morph, however they are applied if you do /morph name Zombie.
For example, if I have this:
(ignore the custom attack and abilities), the regular vanilla zombie morph will be affected. However, if instead of minecraft:zombie I put Zombie, which should work, it doesn't apply the changes to the vanilla morph, however they are applied if you do /morph name Zombie.