Is there an elementary topos which
Yes: take any non-trivial ultrapower of $\mathbf{FinSet}$. Your properties 1–3 are all expressible in the first-order language of categories, so they are preserved by ultrapowers.
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Yes: take any non-trivial ultrapower of $\mathbf{FinSet}$. Your properties 1–3 are all expressible in the first-order language of categories, so they are preserved by ultrapowers.