Corviknight: Expert Belt isn't very good competitively, and I don't really see what Protect accomplishes. Corviknight is better as a Defogger or an attacker (either with Brave Bird or Body Press). The EVs are kind of weird as well, so I'll give you a few new sets:
Corviknight @ Leftovers
Ability: Pressure
EVs: 252 HP / 4 Def / 252 SpD
Careful Nature
- Bulk Up
- Brave Bird
- Roost
- Substitute / Body Press
Corviknight @ Leftovers
Ability: Pressure
EVs: 252 HP / 168 Def / 88 SpD
Relaxed Nature
- Defog
- Roost
- U-turn
- Brave Bird / Body Press
The first one aims to increase Attack and Defense with Bulk Up, making both Brave Bird and Body Press stronger. Roost is able to recover HP, from recoil or otherwise, you may sustain. Substitute makes it easier to set up Bulk Up. The second is more defensive, as a pivot and Defogger for the rest of your team.
Rillaboom: In all honesty, your set is bizarre. Rillaboom is way better as a completely physical attacker with Grassy Surge, rather than a mixed one with Overgrow. The EVs are all over the place, plus you don’t have a Nature. I’m afraid I’ll have to revamp most of your current set, but it’ll make Rillaboom perform better in battle.
Rillaboom @ Life Orb
Ability: Grassy Surge
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Grassy Glide / Wood Hammer
- Drain Punch
- Knock Off
- Swords Dance / U-turn
Grassy Glide is excellent in Terrain, and one of the main reasons Rillaboom is used so much. Wood Hammer can be used for more power, but that leaves Rillaboom without priority. Drain Punch covers Steel and Ice, plus recovers potential lost health. Knock Off can cripple (or at least make it easier to defeat) Pokemon like Toxapex. Swords Dance makes Rillaboom even more of an offensive menace, while U-turn allows it to pivot in and out if necessary.
Duraludon: Dragon Fang isn’t good competitively. Frankly, Duraludon isn’t good competitively, at least in OU. May I suggest an alternate Dragon type and an alternate Steel type? Dragapult is an excellent Pokemon in OU, and one of the best Dragon types all around. Magearna is an absolute terror, and one of the single most potent Pokemon in OU at the moment.
Dragapult @ Choice Specs
Ability: Infiltrator
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Shadow Ball
- Draco Meteor
- U-turn
- Thunderbolt / Flamethrower
Shadow Ball and Draco Meteor are both solid STAB. U-turn uses Dragapult’s excellent Speed to pivot in and out. Thunderbolt and Flamethrower are both coverage, with Flamethrower taking out Ice types and Steel types that wall the set.
Magearna @ Choice Specs
Ability: Soul-Heart
EVs: 252 SpA / 4 SpD / 252 Spe
Modest Nature
- Fleur Cannon
- Volt Switch
- Flash Cannon / Aura Sphere / Focus Blast
- Trick / Aura Sphere / Focus Blast
It can utterly decimate with this moveset, with a ridiculously powerful move in Fleur Cannon, a pivot in Volt Switch, Flash Cannon, and Fighting coverage/Trick. There are other movesets that Magearna can use well, including Calm Mind and Weakness Policy variants, giving you an idea as to how versatile it is. Smogon has several other movesets that all work very well as well.
If you absolutely must use Duraludon (I strongly advise against it), then use a set along these lines:
Duraludon @ Choice Specs / Leftovers
Ability: Light Metal
Shiny: Yes
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Draco Meteor
- Flash Cannon / Stealth Rock
- Thunderbolt
- Body Press
Grimmsnarl: Dark Memory? What on earth? To be quite blunt, the entire moveset is not very good. Grimmsnarl is much better suited to dual screen setting, so here’s a moveset for that:
Grimmsnarl @ Light Clay
Ability: Prankster
EVs: 252 HP / 48 Def / 180 SpD / 28 Spe
Impish Nature
- Reflect
- Light Screen
- Taunt / Thunder Wave
- Spirit Break
Do also note that Regieleki is a very good screen setter as well, and it’s actually in OU. Consider using that.
Toxtricity: Toxtricity is a weird choice for OU, but it can work. It’s more suited to a Shift Gear set, so here’s the Smogon suggestion:
Toxtricity @ Life Orb
Ability: Punk Rock
EVs: 144 Atk / 148 SpA / 216 Spe
Rash Nature
- Shift Gear
- Boomburst
- Overdrive
- Drain Punch
Spiritomb: For the love of all that is good teambuilding, do not use Spiritomb in OU. It’s bad, and severely outclassed. I would instead recommend Dragapult, who is mentioned above, Spectrier, or Mandibuzz. Spectrier is a better offensive choice, while Mandibuzz is better defensively.
Spectrier @ Leftovers
Ability: Grim Neigh
EVs: 112 HP / 20 Def / 172 SpA / 20 SpD / 184 Spe
Timid Nature
- Substitute
- Hex / Shadow Ball
- Nasty Plot
- Will-O-Wisp / Disable
This set can wreak havoc on any opponent that doesn’t resist Ghost. Don’t use Hex if you’re not using Will-O-Wisp.
Mandibuzz @ Heavy-Duty Boots
Ability: Overcoat
EVs: 248 HP / 60 Def / 144 SpD / 56 Spe
Impish Nature
- Foul Play
- Roost
- Defog
- Knock Off / U-turn
This set utilizes Mandibuzz’s defensive capabilities. It can freely pivot with U-turn or remove items with Knock Off, clear away hazards and screens with Defog, heal with Roost, and use Foul Play for a bit of damage against tough physical attackers.
I apologize for changing so much of your team, but quite honestly, it really wasn’t very good. Best of luck, and I hope I helped!
