There has been a lot of Nintendo-related leaks of late, with everything from Super Mario Maker 2 to The Legend of Zelda: Link's Awakening being revealed by anonymous people online before Nintendo had a chance to properly unveil them during a Direct.
The latest leaker isn't some anonymous forum user on the Internet, but is one of the most famous athletes of all time, as Mike Tyson has revealed on Twitter that a new Punch-Out!! game is in development... or maybe he saw the recent news about the original Punch-Out!! being released for the Nintendo Switch in April and confused it for a new game.
It was recently revealed that the original Punch-Out!! is coming to the Nintendo Switch Online service in April, along with Star Soldier and Super Mario Bros.: The Lost Levels. Nintendo made this announcement on its YouTube channels and many different outlets reported on it, including TheGamer.
heard @Nintendo was doing the new “Punch Out” without even contacting me. it wont be the same. my knockouts made the game. thats whack.— Mike Tyson (@MikeTyson) April 4, 2019
It's likely that Mike Tyson heard the news about Punch-Out!! from a news outlet and thought that it related to a new game in the series. It's unlikely that Tyson has insider information concerning upcoming Nintendo titles, especially if they didn't reach out to him for an endorsement, which they aren't likely to do, considering that Tyson has been retired for many years now and there are other prominent boxers that they could pursue to appear in the series.
It was only the early versions of the original Punch-Out!! that included Mike Tyson as the end boss, as the likeness rights to use him in the game expired and he was replaced by a new character called Mr. Dream, which is the version of the game that will be appearing on Nintendo Switch Online.
Nintendo has also made Punch-Out!! games after the original, as a new entry in the series was released for the Nintendo Wii in 2009. The Wii version of Punch-Out!! used original characters (as well as a cameo appearance by Donkey Kong) and didn't involve any famous boxers of the day.
A new Punch-Out!! game for the Nintendo Switch would be awesome and the twin Joy-Cons would make for a perfect alternate control scheme, but it's more likely that Mike Tyson was acting on false information.
Punch-Out!!, Star Soldier, and Super Mario Bros.: The Lost Levels will be available to download for Nintendo Switch Online subscribers on April 10, 2019.