Niantic has published the Three-Strike Discipline Policy for players of Pokémon GO that have been found to be cheating. Full details are posted below.

Pokémon GO - Three-Strike Discipline Policy

At Niantic, we strive to create a friendly and fair gameplay experience for all players. As part of that commitment, we enforce a three-strike policy against cheating. This policy may provide offenders with a series of disciplinary actions that gradually increase in severity and provide multiple opportunities to change their behavior. If offenders reform their ways, they are welcomed back into the game. However, if offenders continue cheating, they will be permanently removed from the game in accordance with the Pokémon GO Terms of Service.

For the purposes of this policy, we define cheating as behaviors that violate the Pokémon GO Terms of Service and Trainer Guidelines, such as falsifying location (GPS location spoofing) and accessing Pokémon GO clients or backends in an unauthorized manner, including through the use of third-party software or add-ons.

A strike serves as a warning. Everyone can make mistakes. That’s why we have created this policy to enable offenders to learn from their mistakes and change their ways. If you have been issued a strike, don’t ignore it. Take action to ensure that you do not commit any further transgressions. If you believe that your account was compromised or hacked, please see this article for tips on securing your account.

Keep in mind that offenders are not always offered three strikes. Some misbehaviors may result in immediate account termination without prior warning.

Strike 1: Warning

Disciplinary actions: If this strike is issued, you will see a warning message within the Pokémon GO app informing you that we have detected cheating on your account.

In addition to this warning, your gameplay experience may be degraded in the following ways for the duration of the warning:

• You may not be able to encounter rare Pokémon in the wild. These Pokémon may not appear on the map or on the Nearby Pokémon tracker.
• You may be excluded from receiving new EX Raid Passes.

Duration: This strike will last for approximately 7 days. After this period, your gameplay experience will fully be restored.

Strike 2: Suspension

Disciplinary actions: If your account is issued a second strike, you will temporarily lose access to your Pokémon GO account. When attempting to log into the game, you’ll be presented with a message stating that your account is suspended. You will not be able to bypass this message.

Duration: This strike will last for approximately 30 days. After that period, your account access will be restored.

Strike 3: Termination

Disciplinary actions: If you receive the first and second strikes and continue to cheat, your account will be permanently banned.

Duration: Permanent

Appealing your punishment

If you believe your account has been terminated in error, you may appeal the termination. We will respond to your appeal after a complete investigation of your account. Please note that due to the high level of accuracy in our detection systems, very few terminations are ever overturned.

Source: https://support.pokemongo.nianticlabs.com/hc/en-us/articles/360001743487-Three-Strike-Discipline-Policy