Not Unova related, but is it true that pupitar move by farting?

That’s a bit crudely put, but … yes.

Actually, it’s quite interesting that you mention this, anonymous, as while scientists don’t necessarily call it that (formally, anyway—we certainly do privately and when not in earshot of a pupitar), it’s known that the gases pupitar specimens emit consist largely of a mix of sulfur, methane, carbon dioxide, and other elements and compounds prevalent in human flatulence.

It is also the exact chemistry of the gases that fill the more inhospitable mines of the Johto region. In fact, the phrase “pidgey in the coal mine” comes from the old practice of bringing a caged pidgey into Johtonian coal mines and using them to detect pupitar nests. This is because when in the vicinity of pupitar nests, the pidgey would, well, faint from the gases pupitar emit from their anal jets. Humans, due to their much larger sizes compared to pidgey, often lasted a little longer—or, at least, long enough to evacuate the field of pupitar gas.