When naturally spawned, only the "brown-robed" Zombie Villagers will appear, the other 4 types don't.
I believe this has been around for quite some time (0.16 perhaps), despite there being 5 (hopefully 6 soon) types of Zombie Villagers.
MCPE-19963
The only Zombie Villagers that naturally spawn are the "brown-robed" ones.
Resolved
Cannot Reproduce
0
(Unassigned)
Unconfirmed
Phone - Android - Samsung Galaxy Note
Android 6.0.1
1.0.3, 1.0.4.0
Retrieved
Cannot reproduce in 1.0.4.0.