On June 12, Niantic announced that they were disabling Pokemon Go's GO Battle League until further notice due to an in-game exploit.
Update: GO Battle League has been finally re-enabled and you can play right now! Niantic have given an update here.
"We’ll bring it back online once this exploit has been addressed," Niantic revealed on their Twitter page. "We apologize for any inconvenience this might’ve caused."
For Niantic to so suddenly disable it and for it to be down nearly 24 hours later shows the gravity of the exploit. In a blog post they even described it as cheating.
Trainers, we’re disabling GO Battle League until further notice, as we’re investigating a serious exploit. We’ll bring it back online once this exploit has been addressed. We apologize for any inconvenience this might’ve caused.
For more on this decision: https://t.co/9q1UQ1R35k
— Niantic Support (@NianticHelp) June 13, 2020
While the game has only been taken down recently, it seems the glitch itself has been pertinent for at least a few days. It isn't clear what caused it.
What is the exploit?
We're certainly not going to tell you how to do it but will explain what it is. Hopefully it will be removed in its entirety when GO Battle League is re-enabled, anyway.
The issue surrounds Melmetal, the steel Pokemon that was added to the franchise in the build up to Pokemon Let's Go. Reportedly it affects other species too - Cresselia, Giratina, Leafeon, Scizor and Swampert - but we were able to find no evidence of this.
The exploit allows trainers to use Charge Moves far more frequently than they should be able to. In the video below from JRskatr, we can see his opponent's Melmetal using a Rock Slide for every 2 or 3 Fast Move attacks - it should be 5.
Obviously this give trainers a hugely unfair advantage, allowing them to almost certainly win the battle. This will not only give innocent trainers unfair losses but propel the cheater to the top of the GO Battle leaderboards.
In a follow up video JRskatr explains that it appears that the trainer using this exploit was able to continue energy generation during JRskatr's Charge Moves. This would explain why the Rock Slides were so incessant.
When will GO Battle return?
This exploit is getting a lot of attention among the Pokemon Go community, so it's no surprise Niantic have acted so swiftly. The trainer in question has reportedly been banned.
With that part complete, it looks Niantic just need to resolve the exploit. That seems to be proving harder than it sounds however, as it has now been a lot more than a week since the mode was taken offline.