Classification: Shinigami, Gotei 13 captain (6th division)
Threat level: Dragon
Physical: Likely island level striking via scaling (has always been portrayed as a rival of Kenpachi, so even if inferior in brute power to Nozarashi he should be able to trade blows with current base Kenpachi unless this balance has been drastically offset)
Destructive capacity: At least city level (doesn't focus in attacks with large destructive capacity), likely country level potency (as of his training with the Royal Guard he has become a top tier, showing his prowess by easily fighting off 5 Stern Ritters by himself)
Durability: At least city+, likely much higher via scaling
Speed: At least massively hypersonic (Has always been a shunpo master and after his training with the Royal Guard he is now so fast he can keep up in combat with 5 Stern Ritters at the same time, each easily being high hypersonic and Candicce likely being massively hypersonic)
Intelligence: Genius. Greatest prodigy his clan has seen, this in a clan that is already well renowned for having prodigies which reach high status in the Gotei 13, like his grandpa Ginrei Kuchiki which was a captain. An extremely calm, composed and analytical combatant.
Stamina: Very high. Can take serious injury and keep fighting, even injuries as serious as slashes along his torso. Has remained fighting efficiently even after having to cut his tendons which caused him to lose control of his hand and foot. Remained conscious for a short while even after an onslaught from his own bankai being wielded by Äs Nödt left him as not much more than a stain on a wall.
Standard equipment: His zanpakuto (Senbon Zakura), and Oken clothing designed by Shutara ever since his training with the Royal Guard.