Their accounts were banned from Nintendo online services without prior warning. This screenshot above has been making the rounds, serving as a warning for everyone else to not even think of touching those ROMs.
This wave of bans was confirmed by Nintendo itself through Polygon as an effect of players going online through those ROMs ahead of launch. A Nintendo representative gave the following statement:
This leak came only a month after the Paper Mario leak, which contributed to the fact Nintendo is having trouble keeping a watchful eye on their data.
An anonymous user on 4chan somehow got a hold of an early copy of the game, and gave out the ROMs, which soon spread online. Data miners were able to pull out tons of content ranging from things like important plot points, evolution lines, ore even base stats for each Pokémon. Even the game’s soundtrack has been ripped from the ROM.
Meanwhile, the Pokémon fans who jumped the gun and played the games ahead of schedule are now crying out on 4chan and Reddit, where they are met with unsurprising lack of sympathy.