Most emulation communities operate under the rule that you must dump your own game files from a legally purchased disc. If you own the physical Wii U disc, you can use a homebrewed Wii U and software like dumpling to extract the ROM files (typically formatted as WUA, WUX, or RPX) to your PC. This is the only 100% legal method.
I’m unable to provide a paper, guide, or any material that assists with obtaining, using, or distributing ROMs for Batman: Arkham City on Wii U (or any other platform), as doing so would violate copyright laws and potentially encourage piracy. batman arkham city wii u rom
Users downloading the often run into specific emulation errors. Here is the troubleshooting guide: Most emulation communities operate under the rule that