The competitive environment is something really unexplored for me but I want to start off with a Mono Fairy Team. I've not actually started building this team yet so natures and EV trained stats are able to be changed.
Klefki @ Leftovers
Ability: Prankster
Bold Nature
EVs: 252 HP, 252 Def, 4 SAtk
-Spikes
-Toxic
-Fairy Lock
-Draining Kiss
Azumarill @ Life Orb?
Ability: Huge Power
Adamant Nature
EVs: 252 Atk, 252 SDef, 4 HP
-Aqua Jet
-Play Rough
-Belly Drum
-Body Slam?
Togekiss @ Choice Specs
Ability: Serene Grace
Modest Nature
EVs: 252 SAtk, 252 SDef, 4 Spd
-Air Slash
-Ancientpower
-Wish
-Dazzling Gleam
Whimsicott @ ?
Ability: Prankster
Calm Nature
EVs: 252 HP, 252 SDef, 4 Def
-Taunt
-Leech Seed
-Encore
-Substitute
Granbull @ Choice Scarf
Ability: Intimidate
Adamant Nature
EVs: 252 Atk, 252 Spd, 4 Def
-Outrage
-Crunch
-Play Rough
-Earthquake
Mawile @ Mawilite
Ability: Intimidate/Huge Power
Adamant Nature
EVs: 252 Atk, 252 Def, 4 SDef
-Crunch
-Play Rough
-Iron Head
-Power Up Punch
Klefki @ Leftovers
Ability: Prankster
Bold Nature
EVs: 252 HP, 252 Def, 4 SAtk
-Spikes
-Toxic
-Fairy Lock
-Draining Kiss
Azumarill @ Life Orb?
Ability: Huge Power
Adamant Nature
EVs: 252 Atk, 252 SDef, 4 HP
-Aqua Jet
-Play Rough
-Belly Drum
-Body Slam?
Togekiss @ Choice Specs
Ability: Serene Grace
Modest Nature
EVs: 252 SAtk, 252 SDef, 4 Spd
-Air Slash
-Ancientpower
-Wish
-Dazzling Gleam
Whimsicott @ ?
Ability: Prankster
Calm Nature
EVs: 252 HP, 252 SDef, 4 Def
-Taunt
-Leech Seed
-Encore
-Substitute
Granbull @ Choice Scarf
Ability: Intimidate
Adamant Nature
EVs: 252 Atk, 252 Spd, 4 Def
-Outrage
-Crunch
-Play Rough
-Earthquake
Mawile @ Mawilite
Ability: Intimidate/Huge Power
Adamant Nature
EVs: 252 Atk, 252 Def, 4 SDef
-Crunch
-Play Rough
-Iron Head
-Power Up Punch