The way I see that is that the artists/designers/whatever probably wanted the backgrounds to be a distinctly different color than the Pokemon, so that the Pokemon are easy to distinguish at a glance.
But that would make it sound like "Potty-geist" when it has nothing to do with going to the toilet...not until you drink its tea, at least.
Random thought: Scald seems like an obvious part of its move list, doesn't it?
Attacks such as Gastro Acid and Worry Seed that shut down or change abilities already don't work on Truant, so there's a chance that Neutralizing Gas won't either.