Sierra is one of three Team Go Rocket leaders that Pokemon GO trainers must battle before they can challenge the organization's boss, Giovanni.The difficult part of battling Sierra and the other members of the trio, Cliff and Arlo, is that the Pocket Monsters they end up using won't be completely known to the player before the fight.Taking note of all the possible Pokemon Sierra can use will enable a trainer to enter battle against her more prepared. Here's how to defeat the Team GO Rocket leader.The Season of Discovery has started in Pokémon GO! 🔎 Different Pokémon are appearing in different parts of the world and hatching from Eggs! Don’t forget to catalog your discoveries with a #GOsnapshot! https://t.co/D1XOXq2HEf pic.twitter.com/4oYvJfxrUe— Pokémon GO (@PokemonGoApp) June 2, 2021Also Read: The best counters for Cliff in Pokemon GO: June 2021 Note: This article reflects the personal opinion of the writer.Also Read: Best counters for Arlo in Pokemon: GO in June 2021How to beat Sierra in battle in Pokemon GOSneaselSneasel in the anime (Image via The Pokemon Company)Sierra's second and third Pokemon can be one of many, but her first Pocket Monster is locked in. The Dark/Ice-type Sneasel won't be a problem for players if they know the best counters to use against it.Sneasel is especially susceptible to Bug, Fairy, Fighting, Fire, Rock and Steel-type moves. These are the best counters to send out against Sierra's Sneasel:Lucario - who knows the moves Counter and Aura SphereConkeldurr - wielding the attacks Counter and Dynamic PunchCobalion - equipped with Metal Claw and Sacred SwordGliscor, Granbull, or AmpharosAmpharos in the anime (Image via The Pokemon Company)Upon knocking out Sierra's Sneasel, players will battle either Gliscor, Granbull or Ampharos next.If Sierra sends out Gliscor, use one of these Pokemon against it:Mamoswine using Powder Snow and AvalancheMewtwo equipped with Psycho Cut and Ice BeamGlaceon who knows Ice Shard and AvalancheWhen battling Granbull, a trainer can use one of these creatures to win:Metagross harnessing the power of Bullet Punch and Meteor MashRoserade who knows the moves Poison Jab and Sludge BombExcadrill with the attacks Metal Claw and Iron HeadAmpharos won't last long against:Groudon equipped with Mud Shot and EarthquakeRhyperior with the moves Mud-Slap and EarthquakeGolurk who knows Mud-Slap and Earth PowerHoundoom, Kingdra, or DrapionDrapion in the anime (Image via The Pokemon Company)Once a player beats Sierra's second Pokemon, there's only one more to conquer before a trainer can claim victory. Sierra will either use Houndoom, Kingdra, or Drapion as her final Pocket Monster.Against Sierra's Houndoom, try using one of these Pokemon:Rampardos with Smack Down and Rock Slide in its arsenalConkeldurr using the moveset that includes Counter and Dynamic PunchKyogre wielding the Water-type attacks Waterfall and SurfIf the Team GO Rocket leader sends out Kingdra, counter it with:Palkia who knows Dragon Tail and Draco MeteorGarchomp equipped with Dragon Tail and OutrageGardevoir using the Fairy-type moves Charm and Dazzling GleamDrapion doesn't stand a chance against these Pocket Monsters:Excadrill harnessing the power of Mud-Slap and EarthquakeGarchomp using Mud Shot and EarthquakeGolurk equipped with Mud-Slap and Earth PowerPlayers of the Pokemon GO mobile game will make quick work of battling this Team GO Rocket leader, as long as they know the right counters to bring with them to the fight. Benefitting from the right type-advantages will allow a trainer to properly counter and defeat all of Sierra's Pokemon.Have you claimed this week’s free one-time bundle containing a Remote Raid Pass and more? Here’s your reminder to do so!— Pokémon GO (@PokemonGoApp) May 26, 2021Also Read How to beat Giovanni in Pokemon GO in June 2021