Greninja is definitely the sexiest Tongueboi, tho. If the movie is anything to go by, Lickitung's licker is pretty much the bigger than an average human torso, making it way too fat and big to do anything beyond, well, licking. Gengar is the same, but gaseous and will probably kill you if the pokedex is anything to go by. Kecleon and Politoed tongues are a bit too thin. And we don't even know if Sobble is a tonguemon in the first place.
But Greninja's tongue is the perfect middleground between all of them: Thin enough to pretty much fit anywhere he wants it to, but still thick enough to fill everything to max capacity. Also long and strong enough to do squeezeplay and all sorts of bondage. Who knows, maybe he can even enhance it with jutsu magic and the like. It's perfect in every way.
