since I was not quite familiar with the character Nightwing I checked Wikipedia and found the following about Nightwing:
Powers and Abilities
Nightwing (like his mentor Batman) has many different gadgets that he uses to defeat his enemies. Most of the gadgets are in the form of small boomerangs; some of them explode, some spread liquid nitrogen to freeze objects, and some are just sharp, which he uses to disarm but not kill. Along with his boomerangs he has a grappling gun, a taser and a retractable quarter staff which measures at six feet long at maximum length and one foot long at minimum length. Nightwing has trained in many different martial arts including Hapkido, Tae-Kwon-Do, Jeet Kune Do, Kumdo, Escrima, Tai Chi, Wing Chun, Aikido, Ninjutsu, Kempo, Karate, Jujutsu, and Judo. Nightwing is also an experienced gymnast and spent several years of his youth in the circus. Along with skills with gadgetry and martial arts, Nightwing is exceedingly intelligent. He uses his detective skills and tactics to out think physically superior opponents.
And on Comicvine I found the following:
Skills & Abilities
Although Nightwing doesn't have any superpowers heh counts with peak athletic strength and endurance of a man who regularly engages in intensive physical exercise.
His detective and martial arts skills are almost at Batman's level, making him one of the best crime fighters alive. Being a master of a half dozen martial arts such as: Judo, Jeet Kune Do, Taekwondo, Aikido, Wing Chun, and Escrima. He also possesses vast training in other martial arts such as Hapkido, Jiu-jitsu, Karate, Savate, Kendo, Ninjitsu, and Tai Chi. He was trained by Batman in everything from escapology to criminology, fencing, stealth, disguise, and numerous other combat/non-combat disciplines. He is among the seven characters in the DCU that fans are considering for best martial artist.
Dick being a prodigious natural athlete, possess a peak human level of agility and acrobatic skills. He is the best acrobat in the DC universe. He is the only person on Earth who can do the quadruple somersault now that his parents are dead (he used to be one of three).
He is a brilliant and experienced strategist with superior leadership skills, he has been the leader of the Titans, the Outsiders, and one time of the Justice League.
Grayson's interpersonal skills and efforts to remain in contact with other heroes makes him a master at rallying, unifying, and inspiring the superhero community, a skill in which he has surpassed his mentor.
*Nightwing's costume has an excellent protection against damage, made Nomex fire-proof,triple-weaved material that has been lined with kevlar and is also insulated against electricity. His suit is made for his fighting style of "move more get hit less" and has less armor in his so he can do so, but can add armor when facing fast and strong foes.
*The suit is light sensitive, darkening when there is more light in the area.
*His mask includes a built-in radio transmitter/receiver and Starlite night-vision lenses.
*Each one of his gauntlets and boots contain eight compartments in which he can store items. They have built into them a self-destruct feature such as the ones in Batman's utility belt.
*Each gauntlet's sections contain a lot of equipment, such as sonic or smoke pellets, modified batarangs (Wing-Dings), knockout gas capsules, and throwable tracers. The right gauntlet also counts with a 100,000-volt stun gun.
*His boot compartments carry important equipment such as flares, a rebreather , a mini-computer equipped with fax, modem, GPS and a minidisk rewritable drive. Also items like lock picks, a first-aid kit, a mini-cellphone, flexi-cuffs, antitoxin assortment, signal flares, wireless listening devices and a small halogen flashlight.
*Nightwing carries in the back of his costume a pair of Escrima sticks.
*Richard also has a specialized muscle car called the "Nightbird" which is built with many parts like those on the Batmobile, such as bulletproof armor and wireless network connections.
*Nightwing's parents also left him a trust fund which was turned into a small fortune Lucius Fox. Nightwing has used it for "maintaining his Nightwing equipment; for purchasing the rights to Haly's Circus, saving Dick's former home from financial troubles; and for secretly buying the apartment building at 1013 Parkthorne Avenue at Blüdhaven which was the home of the first Tarantula.
Now this does sound really impressive and from what I have read Nightwing is a tremendous martial artist.
But if that will be enough to defeat big guns like The Punisher or Bullseye?
The Punisher has taken out opponents which were far more dangerous than Nightwing and I think he would know which weapons to choose to take out Dick. And Bullseye is just a dangerous psycho who can kill with something simple as a paperclip.
No disrepect meant for Nightwing but I think he is not in the same league as Big Pun or Bullseye. To me Nightwing seems to be the perfect sidekick; I am not sure if he can take out heavy-hitters all on his own.
Just my two cents though; YMMV!
Nothing can stop The Juggernaut... NOTHING!