>>31787108The reason doubles is the main format is because it's overall more playable, approachable, and balanced than singles from a competitive standpoint. 3v3 singles is okay (Non legendary ubers like blaziken and mega salamence aren't broken in 3v3), but 6v6 singles is borderline unplayable (Stall, entry hazards, switching every other turn to predict the predictions that the opponent predicted) without ridiculous amounts of balancing by third parties i.e. smogon and you know how popular they are.
Any "official" format couldn't do any sort of smogon style bans (i.e. ban on merit instead of arbitrary labels like "legendary" or "mythical"), which 6v6 singles practically requires. They could, but it would cause a shitstorm due to many disagreeing with or feeling "alienated" by smogon, (citing stupid shit like "Why don't they just allow blaze blaziken or aegislash w/o kings shield") and the Game Freak wouldn't want to acknowledge them anyway, since they'd be admitting that they created an unbalanced mess. Because of this, and the fact that doubles are simply more fun to watch both from an analytical standpoint and a visual one (4 on screen > 2 on screen), doubles is the only metagame VGC will ever use.