Oh you're right, Emerald did put more emphasis on the double battles. Trainers previously in RS that were only single battles, became double battles. B2W2 should definitely follow up with this.Ruby and Sapphire also introduced double battles, but had far fewer than important, they werent correctly incorporated until Emerald which was remake of Ruby and Sapphire, They might have done that just to see if they would get good feedback and then add more or take them out depending on such feedback