VGC is the video game championships. There are official Pokemon tournaments that you can travel to, in order to compete. It is in double battle format, and has different Pokemon restrictions every year. You can win prizes like vacations, Pokemon cards, scholarships, and Pokemon items. Pokemon Showdown is a free battle simulator, which let's you battle without ev training, and you enter all your Pokemon, and play online. It doesn't have doubles yet, but has a variety of tiers, and the battles are well presented. Pokemon Online is like Pokemon Showdown, but with doubles, and other tiers that you can play by joining servers, it is not presented as well though.