Judging by its slender looking body, I wouldn't expect this thing to be any bulkier than Weavile.. although losing the Ice typing that plagued Weavile is a plus.
I'll be interested to see its possible 'new' ability. Look like it could be a Rapid Spinner as well; STAB Dark attacks would certainly scare Ghost away from blocking the spin. If it does having Fighting as its secondary type, it would make a brilliant Spinner, indeed.
edit:
Prediction on Base Stats:
Type: Dark
Ability: Technician / Level Playing Field (ignores priority for all moves, including your own)
HP: 79
Atk: 115
Def: 70
SpAtk: 95
SpDef: 70
Spd: 111
BST: 540
Move Pool of Note:
Attack:
Rapid Spin, Night Slash, Pursuit, Sucker Punch, Superpower, Low Kick, Focus Punch, Psycho Cut, Lick, Dark Pulse, Focus Blast, Ominous Wind, Vacuum Wave, Hidden Power, U-Turn, Fire Fang, Leaf Blade, Dig, Hyper Fang, Roll Out.
Non-Attack/Support:
Nasty Plot, Taunt, Spikes, Agility, Glare, Howl, Mean Look, Moon Light, Protect, Roar, Rest, Sleep Talk, Baton Pass, Substitute.
Notes: This would undoubtedly make him the best Baton Passer, and possibly Spinner in OU. Base 111 speed, with access to Taunt, Nasty Plot, Agility, and Mean Look. An ability to ignore priority, means he won't be easily take out before his pass goes off. It allows him to easily Roar Shuffle Pokemon as well, thanks to ignoring Roar's priority.
With his Dark typing, Ghost will seldom want to switch in, allowing him to freely Spin. He's a decent physical sweeper, thanks to Technician and Howl, and has access to Nasty Plot on the other side.