The turtles are probably stronger since they're mutated reptiles and have more strength for their muscle mass. But that doenst meant they're faster or deadlier when it comes to fighting. And they're a bit young and on the inexperienced side.
I think Bats and Nightwing can take all of them down just cuz they're so well-equipped with tricks and gadgets.
I think hand-to-hand, I'd like to see Bats duke it out with Splinter.
in the comics the turtles killed,,,KILLED multitudes of enemies with their weapons, LEO even sliced off shreadheads,,,,ummmm head. back then they had no qualms about killing an enemy. plus, Anyone that can take shredder and beat him in a 1 on 1 fight has got to be able to hand some ass over to the batbrigade. In the cartoon, it's more even money, but I still give this fight to the turtles. Batman seems to be a better fighter when he's fighting alone, so maybe after the rest of team bat is taken out of the fight, batman wouldn't have to hold back and could take it to the turtles.....but not likely.