To off-topic comment on the post above:
Yeah, this is the actual translation. The point is, that in Latin it is far more common to use "nisi" after "nil" (or "nihil", which means the same). If you look at Wikipedia, none of "nil/nihil sine..." phrases are actually from the times of the Roman empire (while this
is, for example). Thus, it is a kind of Latin that is already influenced by more modern languages.
It is hard to explain because in Latin, negations worked a bit differently than they do now and "sine" as a preposition was strictly subordinating (which you do not feel as strong today). "Nil sine pokemon" implies that "pokemon" is a standard characteristic of "nothing", which THIS "nothing" lacks. As you see, that doesn't make much sense. Since Latin does not have a strict word order, you could also interpret this phrase as "Things without Pokemon: Nothing", which makes more sense but it still sounds like you find that "nothing" on this site, because as I said "sine" is always sub-ordinating. "Nisi" on the contrary puts together equal parts. The meaning would be like "nothing, exception: pokemon" or simply "only pokemon". It's the usual translation for "Nothing without Pokemon".