The reason that chingling forgotten is probably because it only appeared once in the anime. In addition, ir was rather uncommon to see it in the games, as no trainers used it for quite a while. On top of that, chingling never had much use in the video games (especially since it was a baby pokemon) or the TCG (if I recall correctly, only three chingling cards were made). It's evolved form, chimecho, suffered many of these problems, but was prominent in the anime. On top of all this, the design and typing of chingling are utterly forgettable. Chingling is still cute and original in my opinion, but it falls completely flat in every other category.