Poliwrath (M) @ Leftovers
Ability: Water Absorb
EVs: 252 HP / 248 Def / 8 SpD
Impish Nature
- Circle Throw
- Scald
- Sleep Talk
- Rest
Poliwrath acts as a hard check. It can come into any lycanroc attack, it can tank a +2 Splintered Stormshards, it can phase lycanroc for more chip damage on the opposing lycanroc's teammates if rocks or spikes are on the field or straight up kill it and it can rest after damage. After Splintered Stormshards, it doesn't die to a +2 stone edge and can heal up.
+2 252 Atk Lycanroc Stone Edge vs. 252 HP / 248+ Def Poliwrath: 111-132 (28.9 - 34.3%) -- guaranteed 4HKO after Stealth Rock and Leftovers recovery
+2 252 Atk Lycanroc Splintered Stormshards vs. 252 HP / 248+ Def Poliwrath: 212-250 (55.2 - 65.1%) -- guaranteed 2HKO after Stealth Rock and Leftovers recovery
Let's take the worst case scenario, you get the max roll. 65.1 - 6 (lefties) = 59.1 + 34.3 = 93.4. So, even if you have rocks on the field and you come into lycanroc, you can eat a +2 Lycanium z and smash it with scald or phase it.