We have seen all sorts of things that are odd be pokemon
>ufo
>dna
>windchime
>geode
>acorns
>polygons

But what cannot be a pokemon?
Would a car be out of the question?

I am not talking car/bus themed pokemon, I mean a literal genetically engineered car Pokemon you travel long distance on.

Would microscopic lifeforms blown up be too strange?
I heard that the team was afraid of making a pokemon too small wouldn't sit right fighting huge pokemon. However in many rpgs there are tiny enemies that unexpectedly kick everyone's ass.

What do you think? Also, what in your mind cannot be a pokemon