Who’d win?
I think Bucky-Cap. He has the added advantage of years more experience, the cyborg arm and a ruthlessness that Dick Grayson lacks.
What’s the contest?
A fight? What are the constraints? One on one or can they call in their friends? Weapons or no? Whose territory are they in?
Trying to catch a villain? Who? Again, do they have to go it alone, or do they have full access to their assets, including friends?
A direct battle of wits vs each other?
In a mano a mano fight, Bucky’s got it through superior training. Include weapons, given the ‘no kill’ constraint implied by the fact these are both heroes we’re talking about, that puts the advantage onto Dick, who’s got a more varied selection of non-lethal weaponry and defensive gear built into his suit, although the scales could tilt to Bucky’s favour if mobility is a factor, and it’s in NYC or other territory he’s more familiar with. However, ranging across Gotham, or southern Jersey in general, and it’s Dick again.
Able to call in friends…Dick wins the brawl, just by sheer numbers. Titans, League, Gotham capes, Birds of Prey, vs Avengers and SHIELD, or whateverthehell successor organization is going right now.
Catching a villain? Advantage goes to whoever’s rogues gallery they’re normally in, if we’re drawing from known villains.
If a newbie, territory again comes into play - who knows the lay of the land, the local underground, who’s got a relationship with the local cops?
But only if it’s one-on-one. With friends, I have to give that one to Dick, just because he’s got Oracle and Red Robin in his network. Granted, Bucky’s got government contacts, but…Oracle has a tendency to punk the feds when it comes down to that, so I’d give the competition to her ever time.
Brain vs brain… If it were Bruce vs Steve, it’d be an easy call - the Bat, every time. But, Dick’s not Bruce. He’s no dummy, but…Bruce is on a different level.
On the other hand, Dick’s dealt with the Riddler - even only in a support function, that’s got to give him some training in non-standard thinking.
Bucky has killed people in the past, as Bucky, as a Soviet assassin and as Captain America. If he KNEW Nightwing was a hero he wouldn’t kill him, but if he did not and thought it was necessary either to survive or to prevent harm to innocents, he would kill him.
Locked room–Cap.
Varying terrain–open issue.
Night-time…:D. You gotta be kidding me!