This is a legitimate question and i feel silly asking but here goes.
Like the title states, what makes him a zoan? The fact his a lion-turtle isn't that just part of a minks design?
Any sarcasm or rude comments, not appreciated. U_U
\threadHe's a Lion Mink who ate the Kame Kame No Mi, which lets him turn into a turtle. Minks are only ever one animal + Human.
(Would a human who ate the Reindeer fruit be able to use the same forms as Chopper?)