Batman vs Teenage Mutant Ninja Turtles the OVA from 2019 is a crossover animated film that features the iconic characters from DC Comics and Nickelodeon. The film is based on the comic book miniseries of the same name by James Tynion IV and Freddie Williams II.

The plot of the film follows Batman as he investigates a series of crimes in Gotham City that are linked to the Foot Clan, a ninja organization led by the Shredder. Along the way, he encounters four mutant turtles who are also after the Foot Clan: Leonardo, Raphael, Donatello, and Michelangelo. The turtles reveal that they are from another dimension where they were trained by a rat named Splinter, who is also their adoptive father. They also explain that the Foot Clan is working with Ra’s al Ghul, the leader of the League of Assassins, who plans to use a mutagenic substance to transform Gotham’s citizens into animal hybrids. Batman and the turtles team up to stop Ra’s al Ghul and the Shredder from unleashing their evil scheme.
The animation of the film is done in a style that blends the dark and gritty aesthetic of Batman with the colorful and cartoony look of the turtles. The film uses a lot of dynamic action scenes and comic book-like panels to create a visually appealing experience. The character designs are faithful to their respective sources, while also adding some unique touches. For example, Batman has a more angular and muscular appearance, while the turtles have different skin tones and facial features. The film also pays homage to both franchises by including references and easter eggs throughout.

The voice acting of the film is another highlight, as it features some of the most recognizable and talented actors in the industry. Troy Baker voices both Batman and the Joker, delivering a versatile and impressive performance. Darren Criss, Kyle Mooney, Baron Vaughn, and Eric Bauza voice the four turtles, bringing their distinct personalities and humor to life. Rachel Bloom voices Batgirl, who joins the team as a tech-savvy ally. Other notable actors include Tara Strong as Harley Quinn, Tom Kenny as Penguin, John DiMaggio as Mr. Freeze, Carlos Alazraqui as Bane, Cas Anvar as Ra’s al Ghul, and Andrew Kishino as Shredder.
The overall quality of the film is high, as it manages to balance the tone and elements of both franchises in a coherent and entertaining way. The film is not afraid to be dark and serious when it needs to be, but it also injects a lot of humor and fun into the mix. The film respects both fanbases and delivers a satisfying crossover that appeals to both old and new viewers. The film is not perfect, as it has some pacing issues and some underdeveloped characters, but it is still a worthwhile watch for fans of Batman and Teenage Mutant Ninja Turtles.