I don’t think sex with Jigglypuff would be considered Innerspecies. Just like Gardevoir and her relatives, they are some of the most Human like Creatures in the series. From their M&M like anthropomorphic design with nearly no animal traits, to the fact that they wrote them like Underage Human Girls from 3 to 21 years old. Sure the argument or Pokemon being Humans has been made before, but JigglyPuff, Clefairy, Chansey, and even Bellosom are quite literally Humans or at least Alien Humans like in Dr. Who, DC, and Marvel. We could even say Sunny the Sunflower from PVZ is one as well cause written like a Human Girl as well and she never behaves like a Rat or a Dog from what I can tell!