Bisharp
Having 252 Speed is a better choice over 252 HP. 252 Speed and Adamant will let you outspeed Pokemon like 120 Speed Heatran, 64 Speed Tapu Fini, 16 Speed Mandibuzz. These are important because you can not overrely on Sucker Punch for all of them, Swords Dance before Tapu Fini Taunts you, and use Iron Head before Mandibuzz Roosts. Even with max HP, Bisharp isn't even a good soft check to Dragapult and Weavile (which I assume is why you used max HP?). Outside of the lack of Speed EVs, the set is good.
Landorus-Therian
I don't think Landorus-T's lack of reliable recovery is justification to run Heavy-Duty Boots. Leftovers is better because it gives Landorus-T passive recovery as opposed to not having recovery at all with Boots. Having Corviknight, the metagame's best Defogger, on your team is even more reason to not run Boots.
Slowking
Slowking's use is as a great special wall. Running 252 Def and Bold absolutely ruins the Heatran and Nidoking matchup. Slowbro is a better physical wall, but Slowbro doesn't fit very well here, at least compared to specially defensive Slowking, since Heatran and Nidoking run this team over without Slowking.
Slowking @ Heavy-Duty Boots
Ability: Regenerator
EVs: 252 HP / 4 Def / 252 SpD
Sassy Nature
IVs: 0 Atk / 0 Spe
- Scald
- Slack Off
- Future Sight
- Teleport
Corviknight
Having 248 HP / 168 Def / 92 SpD is better and here's why: With those EVs, you won't be 2HKOed by Specs Tapu Lele's Psychic Terrain boosted Psychic after Stealth Rock, you won't be 2HKOed by Choice Specs Dragapult's Shadow Ball from full HP, and you can both absorb physical moves better and soft check Specs Kyurem. I'd use Body Press over Iron Head because it beats bad matchups like Heatran and Magnezone, and OHKOes Bisharp and Weavile. I also think Brave Bird is more useful than U-turn here since it does a lot to Volcarona and Urshifu-Rapid Strike, and because you already have 3 Pokemon with a pivoting move.
Corviknight @ Leftovers
Ability: Pressure
EVs: 248 HP / 168 Def / 88 SpD
Impish Nature
- Brave Bird
- Body Press
- Roost
- Defog
Kyurem
You should use Modest for the extra wallbreaking power, Timid doesn't hit any truly important speed benchmark. Otherwise, the set is good.
Dragapult
Looks good.
