This is a pretty successful defensive team using, at the time, the under appreciated Registeel. Alo + Registeel has come full circle since XY and is good again largely because of Venusaur's presence. Knock Off on Alo makes it easier for the team to handle SubCM Meloetta and other such annoying anti-stall Pokemon. Registeel's use of double status allows it to take out Fletchinder, CM Slowking, Sigilyph, Abomasnow, and keep Mega Glalie in line, while subduing various entry hazard removers. Flygon provides this team with a secondary Fire check and offers hazard control and much-needed offensive presence. Dragon Claw takes out opposing Flygon, prevents Sigilyph from getting a free switch-in, and help deal with annoying Levitate users such as Rotom. Braviary is the team's win condition and exploits certain build's reliance on Alomomola + Diancie as opposed to Alomomola + Steelix, and can still cleave through certain Steelix builds with Registeel wearing it down with Seismic Toss. It also gives this team a better shot at beating annoying anti-stall Pokemon such as Jellicent and Taunt Weezing. The Speed EVs allow Braviary to outspeed Timid Abomasnow, Exploud, etc so I have more Pokemon to revenge kill certain wallbreakers with. Granbull is the team's cleric and one of the best Fighting resists in the tier. Roar is used on this Granbull so that this team can beat Malamar when played properly and disrupt random setup sweepers. Finally, Choice Scarf Drapion is the team's glue and does a lot, such as Pursuit trapping Hoopa, revenge killing various threats such as CM Virizion/Delphox, and absorbing Toxic Spikes. An Adamant nature is used since Drapion either misses out on certain Choice Scarf users already (Flygon, Delphox) or outspeeds them with an Adamant nature anyway (Medicham); the only Choice Scarf user that it would need a Jolly nature for is Sawk, which is not an issue at all for this team and extra power is nice anyhow for annoying things like Jellicent and doing more chip damage to Steelix. Running Speed creep is a good idea on some of these Pokemon though, but I'll keep how much I run to myself.
PS: Thunderbolt with around 24 SpA EVs over Thunder Wave on Registeel should be adjusted so that this team can more adequately take on opposing Braviary.
http://pastebin.com/7FFzxyWw