Except that's not obvious at all (and not a red humanoid with a pitchfork, please learn to read), it requires delving into the lore of the game. You wouldn't get it from looking at the thing, like here:
http://yokaiwatch.wikia.com/wiki/Timidevil
People who cause shitstorms because of video game characters are too lazy to actually take a closer look at the stuff they are complaining about (otherwise they'd realize how groundless their complaints are 99% of the time), so as long as it doesn't look exactly like an easily recognizable demonic thing, it's less likely to catch attention. Alakazam was problematic because its head looks almost exactly like Alakazam and Jynx was problematic because she resembled Blackface. Nothing that has appeared in Pokemon since was like that. We'll probably never have a pitchfork devil in Pokemon.