Having trouble team building

[Mirai]

So I'm trying to make a team to pass the time until sun and moon come out, I got one in mind and was wondering if you guys could help me out with strategies and potential downfalls. If there's any idea please help me out, Like who I could swap any weaknesses out for or if there's anything completely wrong with the team.

I will mostly be using this for spot pass singles and occassionally doubles at the nearby gaming lounge.

So, here goes I'll list em off.

Arcanine @ Leftovers
Ability: Intimidate
EVs: 248 HP / 8 Atk / 252 Def
Impish Nature
- Morning Sun
- Will-O-Wisp
- Flare Blitz
- Extreme Speed

Dragonite @ Lum Berry
Ability: Multiscale
EVs: 252 Atk / 4 Def / 252 Spe
Adamant Nature
- Dragon Dance
- Outrage
- Extreme Speed
- Earthquake

Tyranitar @ Choice Band
Ability: Sand Stream
EVs: 100 HP / 252 Atk / 156 Spe
Adamant Nature
- Stone Edge
- Crunch
- Superpower
- Pursuit

Gengar @ Life Orb
Ability: Levitate
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Shadow Ball
- Sludge Wave
- Focus Blast
- Taunt

Landorus-Therian @ Rocky Helmet
Ability: Intimidate
EVs: 248 HP / 244 Def / 8 SpD / 8 Spe
Impish Nature
- Earthquake
- Stealth Rock
- U-turn
- Stone Edge

Diancie @ Diancite
Ability: Clear Body
EVs: 8 Atk / 248 SpA / 252 Spe
Naive Nature
- Moonblast
- Diamond Storm
- Hidden Power Fire
- Protect

 

[megamisterbeedrill]

the team you use are well balanced , you should start off with landorus's steath rock then dragonite's dragon dance followed up with outrage then when dragonite's defeated either go with gengar's taunt or arcanine's will-o-wisp and tyranitar and diancie can be backup mons if you have trouble , landorus and diancie are a normal tank while dragonite is the sweeper so basically that's a good team to go with

 

[cj-97]

Here's an adjustment I made to that team that tailors a lot more to singles OU. Problem I seen instantly with that team above is that Keldeo could practically run through and destroy it single-handledly. I tried to keep as much as the original squad as I could here but it ended up that other pokemon synergised better with other members of the team. Also I adjusted the EV's so that it works better in in-game battles at level 50.

Tyranitar @ Choice Band
Ability: Sand Stream
EVs: 100 HP / 252 Atk / 156 Spe
Adamant Nature
- Stone Edge
- Crunch
- Superpower
- Pursuit

Lopunny @ Lopunnite
Ability: Limber
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- High Jump Kick
- Return
- Fake Out
- Ice Punch

Landorus-Therian @ Rocky Helmet
Ability: Intimidate
EVs: 244 HP / 12 Atk / 244 Def / 4 SpD / 4 Spe
Impish Nature
- Earthquake
- Stealth Rock
- U-turn
- Knock Off

Amoonguss @ Black Sludge
Ability: Regenerator
EVs: 244 HP / 164 Def / 100 SpD
Bold Nature
IVs: 0 Atk / 30 SpA / 30 Spe
- Spore
- Giga Drain
- Clear Smog
- Hidden Power [Fire]

Volcanion @ Leftovers
Ability: Water Absorb
EVs: 4 HP / 252 SpA / 252 Spe
Modest Nature
IVs: 0 Atk / 30 SpA
- Steam Eruption
- Fire Blast
- Sludge Bomb
- Hidden Power [Grass]

Tornadus-Therian @ Assault Vest
Ability: Regenerator
EVs: 96 HP / 160 SpA / 252 Spe
Hasty Nature
- Hurricane
- Superpower
- U-turn
- Knock Off

 

[Mirai]

Here's an adjustment I made to that team that tailors a lot more to singles OU. Problem I seen instantly with that team above is that Keldeo could practically run through and destroy it single-handledly. I tried to keep as much as the original squad as I could here but it ended up that other pokemon synergised better with other members of the team. Also I adjusted the EV's so that it works better in in-game battles at level 50.

Tyranitar @ Choice Band
Ability: Sand Stream
EVs: 100 HP / 252 Atk / 156 Spe
Adamant Nature
- Stone Edge
- Crunch
- Superpower
- Pursuit

Lopunny @ Lopunnite
Ability: Limber
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- High Jump Kick
- Return
- Fake Out
- Ice Punch

Landorus-Therian @ Rocky Helmet
Ability: Intimidate
EVs: 244 HP / 12 Atk / 244 Def / 4 SpD / 4 Spe
Impish Nature
- Earthquake
- Stealth Rock
- U-turn
- Knock Off

Amoonguss @ Black Sludge
Ability: Regenerator
EVs: 244 HP / 164 Def / 100 SpD
Bold Nature
IVs: 0 Atk / 30 SpA / 30 Spe
- Spore
- Giga Drain
- Clear Smog
- Hidden Power [Fire]

Volcanion @ Leftovers
Ability: Water Absorb
EVs: 4 HP / 252 SpA / 252 Spe
Modest Nature
IVs: 0 Atk / 30 SpA
- Steam Eruption
- Fire Blast
- Sludge Bomb
- Hidden Power [Grass]

Tornadus-Therian @ Assault Vest
Ability: Regenerator
EVs: 96 HP / 160 SpA / 252 Spe
Hasty Nature
- Hurricane
- Superpower
- U-turn
- Knock Off

My only real problem with your team suggestion is that I was trying to build a team around Diancie mega as a late sweeper, with Tyran/Dragonite taking the early game, also Volcanion is banned at the game shop I play in doubles at lol

 

[cj-97]

Volcanion ban?