The Team GO Rocket Leaders of Pokemon GO are formidable.
Leader Sierra, just like the other Team GO Rocket Leaders, change up their teams quite often. The team used the last time they faced Sierra may not be the best choice the next time around.
She has a wide range of Pokemon in her party. They can range from Dark-types, Ground-types, Ghost-types, and more. April 2021 sees three potential Pokemon for Sierra as her second and third battlers in Pokemon GO.
The best counters to use against Sierra in Pokemon GO - April 2021
Each Team GO Rocket Leader has three Pokemon. The first one is almost always the same, while the second and third can rotate between three Pokemon a piece. This makes prepping for these Pokemon GO battles a little harder.
A good tip is to battle Sierra with some weaker Pokemon to get an idea of who she might have on her team. Then rematch with the right counters to defeat this Team GO Rocket Leader.
Carvanha is a Water/Dark-type. Pokemon such as Torterra, Togekiss, Scrafty, and Hydreigon will certainly help Pokemon GO trainers defeat it.
Hippowdon is a pure Ground-type. That makes Torterra another great choice here, along with Roserade, Kyogre, Rhyperior, and Roserade.
Porygon-Z is a Normal-type, weak to just Fighting-type Pokemon. Truly, any of the above could take care of it, but Fighting-types like Machamp, Hariyama, and Lucario would deal with it swiftly.
In Pokemon GO, Leader Sierra's Mismagius only knows Ghost-type moves. Normal and Dark-type Pokemon with Ghost-type attacks can take it out, such as Krookadile, Ursaring, Tyranitar, or Poison-type Muk.
Houndoom is a Fire/Dark-type Pokemon. Fighting, Ground, Rock, or Water-type moves will make it easy work. Rampardos, Kingler, Conkeldurr, and Kyogre are great choices.
As a Ground/Dragon-type Pokemon. Flygon is pretty powerful in Pokemon GO. Trainers should look to use Fairy, Ice, or Dragon moves on it. Pokemon such as Gardevoir, Clefable, Alolan Ninetales, or Articuno will do the trick.
Sierra's last possible option is Walrein. Torterra would be another solid option here, along with Tangrowth, Alolan Exeggutor, Metagross, and Melmetal. The Ice/Water-type has some solid weaknesses.