This is not a teambuilder!
So I have played through this game three times, all we different starters and Pokemon. And throughout all of the games I have played through, I now know, the best team for the game. PLEASE NOTE THAT THIS IS ONLY MY OPINION
Delta Venusaur (F) @ Delta Venusaurite Ability: Regenerator EVs: 252 HP / 252 SAtk / 4 SDef Modest nature
- Calm Mind
- Psychic
- Moonblast
- Psycho Boost
Delta Snorlax (M) @ Leftovers Ability: Overcoat EVs: 252 Atk / 252 SDef Careful nature
- Curse
- Leaf Blade
- Crunch
- Power Whip
Delta Bisharp (M) @ Flying Gem Ability: Defiant EVs: 4 HP / 252 Atk / 252 Spe Jolly nature
- Bulk Up
- Brick Break
- Drain Punch
- Acrobatics
Delta Gardevoir (F) @ Life Orb Ability: Lightningrod Modest nature
- Calm Mind
- Ice Beam
- Thunderbolt
- Livewire
Tyranitar-A (M) @ Tyranitar Armor Ability: Sand Stream EVs: 252 HP / 252 Atk / 4 Def Adamant nature
- Rock Slide / Stone Edge
- Earthquake
- Crunch
- Dragon Dance
Clawitzer (M) @ Sea Incense Ability: Mega Launcher EVs: 4 HP / 252 SAtk / 252 Spe Modest nature
- Water Pulse
- Dark Pulse
- Aura Sphere / Scald
- Dragon Pulse / Scald
Well, here it is. 
Please comment down on what you think the best Game-play team is. 