Hello,
Currently, there are no BATMAN implementations available in the ns-3 app store. However, you can find some on GitHub. Here is a link to a document with various implementations of non-native routing algorithms in ns-3:
Implementations of Non-native Routing Algorithms in ns-3
There is a BATMAN implementation designed for sensor networks. Modifying this to suit your needs might be a better solution than starting from scratch.
Have a great day,
Hugo