I had quite a bit of success with my team, I went 9-1 but my only loss was because of a costly misclick. Here's the team I was using:
Sableye @ Leftovers
Ability: Prankster
EVs: 252 HP / 252 Def / 4 Spe
Bold Nature
- Will-O-Wisp
- Recover
- Taunt
- Foul Play
Rhyperior @ Assault Vest
Ability: Solid Rock
EVs: 116 HP / 252 Atk / 140 SpD
Brave Nature
IVs: 0 Spe
- Earthquake
- Stone Edge
- Ice Punch
- Metal Burst
Gyarados @ Gyaradosite
Ability: Intimidate
EVs: 4 HP / 252 Atk / 252 Spe
Adamant Nature
- Dragon Dance
- Waterfall
- Earthquake
- Crunch
Salamence @ Salamencite
Ability: Intimidate
EVs: 4 Atk / 252 SpA / 252 Spe
Naive Nature
- Hyper Voice
- Fire Blast
- Draco Meteor
- Double-Edge
Gardevoir @ Choice Scarf
Ability: Trace
EVs: 4 Def / 252 SpA / 252 Spe
Modest Nature
IVs: 0 Atk
- Moonblast
- Psychic
- Shadow Ball
- Trick
Breloom @ Focus Sash
Ability: Technician
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Spore
- Mach Punch
- Bullet Seed
- Rock Tomb
They all proved to be pretty useful, and I generally had a good matchup against every team I faced. Sabeleye was probably the most useful, as the competition is very physically heavy and the choice between the two megas was really useful as pretty much every team was weak to one or the other. Rhyperior was the least useful, as I only had one opportunity to bring it due to the abundance of Azumarill, Swampert, and Breloom, however it did come in handy in the match I brought it as it was successfully able to take out my opponent's Latias and Gardevoir.
Sableye @ Leftovers
Ability: Prankster
EVs: 252 HP / 252 Def / 4 Spe
Bold Nature
- Will-O-Wisp
- Recover
- Taunt
- Foul Play
Rhyperior @ Assault Vest
Ability: Solid Rock
EVs: 116 HP / 252 Atk / 140 SpD
Brave Nature
IVs: 0 Spe
- Earthquake
- Stone Edge
- Ice Punch
- Metal Burst
Gyarados @ Gyaradosite
Ability: Intimidate
EVs: 4 HP / 252 Atk / 252 Spe
Adamant Nature
- Dragon Dance
- Waterfall
- Earthquake
- Crunch
Salamence @ Salamencite
Ability: Intimidate
EVs: 4 Atk / 252 SpA / 252 Spe
Naive Nature
- Hyper Voice
- Fire Blast
- Draco Meteor
- Double-Edge
Gardevoir @ Choice Scarf
Ability: Trace
EVs: 4 Def / 252 SpA / 252 Spe
Modest Nature
IVs: 0 Atk
- Moonblast
- Psychic
- Shadow Ball
- Trick
Breloom @ Focus Sash
Ability: Technician
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Spore
- Mach Punch
- Bullet Seed
- Rock Tomb
They all proved to be pretty useful, and I generally had a good matchup against every team I faced. Sabeleye was probably the most useful, as the competition is very physically heavy and the choice between the two megas was really useful as pretty much every team was weak to one or the other. Rhyperior was the least useful, as I only had one opportunity to bring it due to the abundance of Azumarill, Swampert, and Breloom, however it did come in handy in the match I brought it as it was successfully able to take out my opponent's Latias and Gardevoir.