You might get away with entering it in one of the stout (13) styles, maybe 13E, even if you put cocoa in it. If there is a strong chocolate flavor, I wouldn't bother. 2 ounces shouldn't too obvious.
As far as the Specialty area goes, it should be something unusual and many, many people do chocolate stouts.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
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