[Nyx]

http://www.pokemon.com/us/pokemon-tcg/play-online/

Just recently found this even though apparently it has been out for ages and started playing it a bit. It's incredibly fun and reminds me of the days when I spent every cent I got on packs to play with and trade at school. It works like a dumbed down version of Hearthstone; you can buy packs in the shop or your can earn your cards simply through prizes in matches. There are also tournaments in game that can be entered to win big rewards ingame (lots of booster packs, etc.)

If anyone decides to play, my name is imTarew so feel free to add me and we can play a match or something!