James Wan's Aquaman movie is revealed to get a PG-13 rating, which is pretty much a given, as it has received the rating for "sequences of sci-fi violence and action, and for some language."
Deborah Snyder and Zack Snyder are also listed a executive producers, which is most likely due to their earlier contracts that make them associated with the Justice League characters.
Geoff Johns, Jon Berg and new DC films president Walter Hamada are also listed as executive producers.
The updated info comes from the official Aquaman WB website under the "credits and ratings" section:
Regarding if Zack Snyder really had much or anything to do with Aquaman is in doubt as the film looks to be all James Wan's, and in additon, Wan didn't want it attached to any of the Justice League characters or DCEU.
“I wanted to keep the story to the world of Aquaman and not have to worry about what other characters are doing in their films and how that would affect us," Wan said in a previous interview. "I just thought the simplest way was to keep it clean — keep it simple and let it be an Aquaman story.”
Actually when James Wan was first in talks to direct the movie, he told them he wanted it to be independent:
“I told them I understand and respect that it’s part of a bigger universe but at the end of the day I have to tell the story I want to tell, and I want to develop the character as well,” Wan previously said. “It was something the studio was respectful about … .in my movie he starts off one way and becomes very different by the end. It’s a classic hero’s journey. I equate our story to The Sword and the Stone, it’s a very Arthurian story about a journey to becoming king.”
Aquaman has a December 21, 2018 release starring Jasom Momoa in the titular role, Amber Heard as Mera, Patrick Wilson as Orm the Ocean Master, Yahya Abdul-Mateen II as Black Manta,Willem Dafoe as Nuidis Vulko, Temuera Morrison as Thomas Curry, Nicole Kidman as Queen Atlanna and Dolph Ludgren is King Nereus.