Corey Graves is basically a street thug. Hilariously, his finisher is some complicated leg submission. Fits PERFECTLY with that gimmick.
Kruger is doing an African poacher/hunter gimmick.
Erick Rowan is an underling to Bray Wyatt and is tag teaming with Luke Harper, the former Brodie Lee on the Indies. Bray Wyatt is Husky Harris, except now he's awesome and has a cult leader gimmick. Rowan and Harper are just these big guys who beat up their opponents and then just walk back to Wyatt with this dazed, zombie-esque look on their face that you can CLEARLY see means he's controlling them. Rowan originally had a Viking gimmick or something, but they changed that. Now he wears a green jump suit. Harper is basically just wearing what he did as Brodie Lee, they really didn't change him except that he looks like a deranged underling and doesn't talk.
Bronson has an MMA gimmick.
Judas Devlin is basically a Hipster version of Damien Sandow, but I've never seen him on NXT ever, except when everybody ran down to the ring to congratulate Big E Langston on winning the title.
Sylvester Lefort hasn't shown up on NXT to my knowledge, but he was using a gimmick where he dressed up like a Spartan from 300 on the Indies. They had to have changed that because his NXT picture looked different. He was trained by Lance Storm, for whatever that's worth.
Don't really know about the others. I haven't caught every week of NXT but they don't seem like regulars from what I have caught.
Nobody really has a gimmick that sticks out that well except Wyatt's cult leader gimmick. That's amazing.