Pokémon GO Sierra July 2020 counters are fairly similar to ones in the past.
Pokémon GO users now have the chance to battle Sierra, a Team Go Rocket Leader. Sierra is one of three leaders that can be found in a Team Go Rocket balloon that can be found using a Rocket Radar.
Pokémon GO Sierra July 2020 Counters Guide
Unlike Team GO Rocket grunts Jessie and James, Sierra and the rest of the leaders use more powerful Pokémon. Sierra's lineup includes Beldum or Lapras as her first Pokémon. Her second Pokémon can be Exeggutor, Lapras or Sharpedo. Her final pokemon can be Houndoom, Shiftry or Alakazam.
Beldum is a Steel-type and Psychic-type that uses two Normal-type moves. This makes Beldum vulnerable to Fire, Dark, Ground, and Ghost-type. Bringing Pokémon such as Darkrai or Flareon would be good choices. Darkrai is also a good pick against one of Sierra's third Pokémon, Psychic-typed Alakazam.
Lapras provides a bigger challenge as Lapras is a Water and Ice-type. Some good counter to Lapras includes Lucario, MelMetal and Regice. Lucario may also be used against Sharpedo, a Dark and Water-type Pokémon.
Houndoom's weaknesses are much easier to exploit due to its Fire and Dark-typing. Swampert and Tyranitar are solid choices to counter Sierra's third Pokémon. Shiftry is slightly more difficult to deal with but is the weakest to Bug-type due to it being a Grass and Dark-type. Volcorona and Yanmega are good choices as both of them are Bug-type.
For beating Sierra, a player may receive 1,000 Stardust along with one Unova Stone, one Sinnoh Stone, one Max Revive, three Revives, one Max potion and three Max Potions. Defeating her also grants you the chance to capture one of the shadow Pokémon used by the leader.