Yes they will be. The story cover is already a hint itself. I always wondered before how the battle would be if Batman in his superman-proof armored (which we have seen from the movie "Dawn of Justice") have a face-off with Iron Man in his nanotech suit? Hmmm. I'm already preparing myself for the challenge.
There will be other characters from Marvel who will appear as the story goes (X-men and Fantastic Four both have roles too). Spiderman and Doctor Strange will make a special appearance too. I just try to minimize the number of characters in a chapter as to not overwhelm the readers when reading.
The main characters is Batman and Iron Man. They may not seem like it for now but they will be and you'll find out soon.
However, there won't be any mention of Thanos or Darkseid. Even infinity stones and mother boxes. This is an AU so I won't be following the canon. Though rest assured, the Avengers and Justice League will face some formidable enemies in the nearest future.
This is a mystery so I'd leave the plot being figured out by the readers on their own.
Thank you for the comment!
YourDearestJuliet