Rate my OU singles team

Question

Making a team and was wondering about possible improvements.

Volcarona @ Buginium Z
Ability: Flame Body
EVs: 248 HP / 112 Def / 148 Spe
Timid Nature
- Quiver Dance
- Bug Buzz
- Roost
- Flamethrower
Special attacker. The whole team is based on him

Diancie-Mega @ Diancite
Ability: Magic Bounce
EVs: 4 Atk / 252 SpA / 252 Spe
Hasty Nature
- Moonblast
- Diamond Storm
- Earth Power
- Stealth Rock
Magic bounce user, which prevents the opponent from setting up stealth rocks.

Tapu Bulu @ Choice Band
Ability: Grassy Surge
EVs: 84 HP / 248 Atk / 176 Spe
Adamant Nature
- Horn Leech
- Superpower
- Wood Hammer
- Stone Edge
Physical attacker

Kommo-O @ Leftovers
EVS: 250 HP/ 240 SpD / 16 Spe
Ability: Bulletproof
- Stealth Rock
- Protect
- Earthquake
- Dragon Tail
Special Tank. Do you think two stealth rock users is too much?

Slowbro @ Rocky Helmet
Ability: Regenerator
EVs: 252 HP / 0 Atk / 252 Def / 4 SpA / 0 SpD / 0 Spe
Bold Nature
- Scald
- Slack Off
- Psyshock
- Thunder Wave
Defensive tank/pivot

Serperior @ Choice Scarf
Ability: Contrary
EVs: 0 HP / 0 Atk / 4 Def / 252 SpA / 0 SpD / 252 Spe
Timid Nature
- Leaf Storm
- Glare
- Defog
- Knock Off
Defog user

Comments

Slowbro is outclassed by Toxapex. I suggest you use Toxapex instead. :P

I don't think you need two Stealth Rock users, so I suggest replacing Diancie's SR with Hidden Power [Ice]. :P

Bug is a poor offensive Typing; You can still use Bug Buzz, but bugium-Z is a Poor Choice IMO. I think you should Use Firium-Z instead, Give Volcarona Psychic instead of Roost and Psychium-Z, or use a Z-move on a different Pokémon. :P

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I was thinking about replacing tapu bulu with offensive kommo-o, and replacing special defensive kommo-o with celesteela. I dont really like toxapex because i feel like i lose momentum when i use it; however, i'll try it.