Very good fight but I gotta go with Ra's , he trained batman, he brought Jason Todd back from the dead, is responsible for the creation of atleast 7 notable supervillains and a few heros and is just a bastard
Hm... Shredder has always been Superhuman, but Ra's is a master of so very many martial arts. I suppose it would come down to whether Ra's can finish things quickly. Because the longer things go on, the more likely Shredder's almost superhuman strength will show the difference between the two.
If they get subordinates too though, Ra's stands a much better chance. The League of Assassins has some very deadly members, while the foot has about one or two notable fighters.
Lets go with the newest version from the 2013 cartoon, since he seems to have about the same amount or resources as Ra's and I kind of seeing this fight being like Robotnik and Wiley and both Shredder and Ra's sending out both of their respected forces at each other
Well in that case, given the general ineptitude of Shredder's lackies would probably get slaughtered besides Fishface, Karai, and Chuck Norris (it's fun saying he's Chuck Norris), but Ra's without a plan might be outclassed by the Shredder, or has he ever pulled off any superhuman feats?
Ra's has more experience fighting, but Shredder's skills move into superhuman, doing stuff like messing up Dogpound with his fists when the turtles couldn't scratch in their first fight even with their weapons.