NFE PhysDef Rocks (Hippopotas) @ Eviolite
Ability: Sand Stream
EVs: 248 HP / 252 Def / 8 SpD
Impish Nature
- Stealth Rock
- Slack Off
- Earthquake
- Whirlwind / Toxic
Optional Move(s): 
- Curse
- Rock Slide 
- Rock Tomb
- Yawn
Optional Item(s): 
- N/A
Optional Ability:  
- Sand Force
Optional EV/IV(s): 
- 248 HP / 4 Def / 252 SpD (Careful)
Overview: Hippopotas is a good role compressor with access to both Stealth Rock and Whirlwind. Thanks to its solid HP and Defense stats and access to reliable recovery, it also makes for a reliable defensive wall, which can check physical attackers. However, it's quite passive and struggles to deal with Pokemon with a Ground-type resistance or immunity. It is also quite easy to revenge kill it on the special side due to its average Special Defense and poor Speed.
PhysDef Rocks: Stealth Rock passively chips Pokemon on entry. Slack Off improves Hippopotas' longevity, letting it switch in multiple times throughout a game as a reliable check to physical Steel- and Poison-types, such as Pawniard, Alolan Grimer, Klang, and Metang. It can also check physical Fire- and Ground-types such as Monferno, Combusken, Gabite, and Krokorok. Earthquake is a solid STAB attack which allows it hit Fire-, Steel-, and Poison-types, such as Monferno, Klang, and Mareanie, hard and even deal decent damage to neutral targets. Whirlwind phazes opponents, preventing them from setting up on it as well as wearing down the forced switch-ins with potential sand and hazards chip. Toxic can be used instead of Whirlwind to cripple common switch-ins such as Servine, Quilladin, and Marshtomp.
Checks and Counters: Strong special attackers, especially Water- and Grass-types such as Frogadier and Servine, threaten Hippopotas out due to its middling special bulk. Pokemon immune to Ground-type moves, such as Haunter, Misdreavus, and Togetic, can easily switch into Hippopotas and can deal significant damage to it with their attacks, cripple it, or Defog away Stealth Rock. It is also very susceptible to Taunt, which stops it from phazing targets or spreading status.
Optional EV/IV(s): An alternative spread of 248 HP / 8 Def / 252 SpD with a Careful nature lets Hippopotas become a special wall to better check offensive special threats like Kadabra, Electabuzz, and Magmar.