A few months prior to the release for RPA: The Ultimate Battle, some people were able to get information about the new game and reveal it. These include characters, modes and other information about the game. This is a list of most of the leaks for the game before the release and for DLC.
These are the leaks that turned out to be true.
Bongi6 and Omega X the Hedgehog Leak
On September 20th, 2014, someone was able to get some screenshots of two unlockable characters for RPA: The Ultimate Battle that had not yet been revealed. The person got screenshots of Bongi6 and Omega X and uploaded them to a website to discuss the game. Some people classified these as fake due to Omega X already being confirmed as a boss character but the photo's were taken down by Unknown's Company after a few hours and the next day, revealed Bongi6 as a playable character for the game confirming Bongi6 for the game but the official announcement for Omega X being playable was let off until the RPA: The Ultimate Battle Nintendo Direct Presentation (27.11.14).
These are the leaks that turned out to be fake.