Absolutely. And I'd like to cap the size range from one size smaller to one size larger. I don't want these things becoming Colossal dragons.
I'd rather not have them grow to Huge. Just Medium or Large should cover plenty of possibilities.
Upon reflection, I do like the idea of it taking on animal form as well as humanoid. How about:
Change Shape (Su): Three times a day, a zebracorn can take on the form of any Medium or Large-sized animal or humanoid. Its favourite form is a handsome, black-skinned human.
Here's a thought. If it turns into a human it will lose its horn, which means it can not use its
cure wounds or
neutralize poison SLAs. I fancy having it be able to deploy its horn in its changed shape. Something like:
Change Shape (Su): Three times a day, a zebracorn can take on the form of any Medium or Large-sized animal or humanoid. Its favourite form is a handsome, black-skinned human.
A zebracorn retains its horn while shapechanged. It can use its horn as a primary or secondary attack if it wields weapons when in humanoid shape. A shapechanged zebracorn can hide its horn by retracting it into its forehead, leaving behind a star-shaped mark or "blaze". Retracting or deploying its horn is a swift action.
I just like the idea of it zipping a horn out from its forehead while it wails away with a battleaxe. There's also something gonzo-ly folklorish about a shapechanging creature with a retractile horn.
Finally, there's the question of weapon proficiency. We've got "Though the human-zebracorn carries no weapons, he or she can easily use any weapon it has ever seen a human use." I would interpret that as:
A zerbacorn is proficient in all shields as well as all simple and martial weapons, but it must change shape into humanoid form to wield them. It has no proficiency in armour.
We can add it to the description.
