Legendary Battle Raids are a crucial piece of Pokemon GO's PvE experience and many trainers want to make sure they approach the raids in the most efficient way possible. Oftentimes, that means preparing ahead of the battle and saving a counter roster that exploits the current boss' weaknesses with the best move sets possible. That sort of early prep work can help save wasted Raid Passes and ensure players earn as many Premier Balls as possible for the encounter reward.