I finally got around to reading BATMAN/TEENAGE MUTANT NINJA TURTLES years after having reviewed the OAV years ago.
Plot-wise, there's not much to add, since the video closely followed most of the beats of the GN. The Turtles, Splinter, Shredder and the Foot Clan cross from their dimension into Batman's Gotham. While Shredder makes an alliance with Ra's Al Ghul, Batman and Damian-Robin fight the Turtles before becoming buddies. There's no Batgirl in the GN, but there's an early section in which Killer Croc meets the Turtles. I guess that there would have been no point for Croc to appear in the Arkham scene in which a bunch of Bat-foes get turned into half-animals. The physical action of the OAV was more bracing, but artist Freddie Williams II, by chance or design, has an art-style reminiscent of the way the original TURTLE-artists drew the characters with a rough Corben-esque style.
My OAV review does not mention writer Tynion's subplot re: all the action taking place on the anniversary of the deaths of Batman's parents, and without checking I think it a safe bet it was excised. This lends the GN a gravity the OAV does not possess, particularly in a scene where the Caped Crusader gives the hothead Turtle Raphael a primer on Why a Filthy Rich Plutocrat Became a Crimefighter.
