I'm a little over .500 in singles ranked, but my team ATM is:
Timid Protean Froakie (ice beam, grass knot, uturn, extrasensory) Life Orb
Jolly Thick Fat Mamoswine (Earthquake, Rockslide, Ice Shard, Icicle Crash) Assault Vest
Jolly Multiscale Dragonite (Earthquake, Dragon Dance, Rock Slide, Outrage) Leftovers or Weakness Policy
Jolly MegaLucario (Swords Dance, Crunch, Bullet Punch, Close Combat)
Adamant Huge Power Azumarrill (Belly Drum, Aqua Jet, Superpower, Play Rough) HP-restore Berry/Splash Scale
Timid Gengar (Sludge Bomb, Thunderbolt, Shadow Ball, Destiny Bond) Focus Sash
This team is ballin'. All 4-5IV outstanding's with perfect EVs/natures. When I lose, it's due to skill and rarely pokes; there's not many Pokemon combinations that scare me too badly. Protean Froakie usually starts and if he KOs the first Pokemon in the first hit, it's usually a wrap.
Dragonite is the Brave Bird/Aegislash counter. Mamoswine is just a baller(used on dragon heavy teams). Azumarrill owns dragons and walls. 1 belly drum and it's just a match-ending super murderer. Lucario for walls like Ferrothorn and Snorlax. Gengar is usually destiny bond bait for anything else that falls through the cracks(Rotom!!!).
The only thing I consistently have trouble against is Mega Mawile/Trick Room teams. Everything else is cool.