I tried replicating a Prankster Sweep, but in LC. I thought it would work, but when my Riolu used Roar, it didn't go first. Is it a glitch, certain rule in LC, a mod that disables Prankster when there are entry hazard, or something else?
http://replay.pokemonshowdown.com/gen7lc-579720785 <-- Battle Replay
Roar has -6 priority and under Prankster, it has -5