Would absolutely love it if this would (have) exist(ed). And I thought about it quite a lot, not when I started collecting Pikachus, but also in the past as 12 year old kid. Would be so cool to have a single database with EVERY SINGLE Pokémon card that exist (including how many of them exist per, including misprints - on the detail-level of my collections 
).
Unfortunately websites like Bulbapedia, Serebii, Pokémon-Paradijs, etc. to name a few (oh, and the E4 Forum of course!!) are the sources we’ll have to use. Luckily those are also pretty extended so far, especially Bulbapedia. Too bad it doesn’t contain a lot of languages / detail-variations.
But back on topic: Yes, I would love to just add my Pikachu and Seviper wanted threads to a website, and if someone has a card for sale I still need they can contact me; or send me a picture + invoice for all I care. 
Greetz,
Quuador