>>28671519Doubles is:
A.) Faster, therefore it is more stream-friendly and is easier to run more matches in a day
B.) Allows you to use more pokemon at a time (Remember, Gamefreak's "Official" 1v1 rules would follow Battle Maison, where you only use 3v3)
C.) Pokemon who are built for doubles can't function in singles, but pokemon built for singles can totally function in doubles, therefore more pokemon are ultimately viable in doubles.