...I just read over the heading of the Zinc Oxide article, and read through it's physical and electrical properties headings. Nowhere does it say that it is a "low-loss dielectric", nor does it imply it.
Here is a key passage.
"The powder is widely used as an additive into numerous materials and products including plastics, ceramics, glass, cement, rubber (e.g. car tyres), lubricants,[1] paints, ointments, adhesives, sealants, pigments, foods (source of Zn nutrient), batteries, ferrites, fire retardants, first aid tapes, etc."
It is merely an additive that you labeled with a title to give it permissibility in your argument.
"ZnO is often called a II-VI semiconductor because zinc and oxygen belong to the 2nd and 6th groups of the periodic table, respectively. This semiconductor has several favorable properties: good transparency, high electron mobility, wide bandgap, strong room-temperature luminescence, etc."
Now I shall continue further by quoting another article.
"Permittivity is a physical quantity that describes how an electric field affects, and is affected by, a dielectric medium, and is determined by the ability of a material to polarize in response to the field, and thereby reduce the total electric field inside the material. Thus, permittivity relates to a material's ability to transmit (or "permit") an electric field."
The problem with this is that at higher temps, Zinc Oxide conducts electricity in a limited way at room temp, which in Pikachu's body would be certainly above that. That means ZnO is a conductor in Pikachu's body.
From the "List of semiconductors" article.
"Semiconductor materials are insulators at absolute zero temperature that conduct electricity in a limited way at room temperature."
Get the picture now? Also, if you read the article. Zinc Oxide is inorganic, meaning that making it naturally is extremely unlikely, even with evolution. We don't naturally form ZnO in our bodies, and Pikachu being a mammalian animal-type makes it just as unlikely.
Also, see my post earlier that explains why it would severely damage Pikachu. The Sodium Chloride in his blood would cause Pikachu to short circuit just like Pichu does due to it having a protonic effect on the charge.
DO NOT try to BS out of this, there is nary a place where blood vessels do not reach. We, as I explained and proved with visual proof in my earlier post in the debate thread, have veins that reach into our cheeks. To deny their existence there is to deny reality.
Therefore by logic, Pikachu would as well, and because of the close vicinity, the short circuit will happen.