I find myself using them pretty much mid to late game if at all. I usually wait till I have the advantage on the matchup and try and predict the swap. Either that or buff it up vs. a wall that wouldn't have Roar/Whirlwind.
It also really depends on the stat increase move you're using like stated before, and what pokemon you are using it on.
It also really depends on the stat increase move you're using like stated before, and what pokemon you are using it on.
