I downloaded and made my Pokemon Trainer Club account with an email address that did not have the permission to purchase or store any payment info on my account. I made a new Gmail account that would have the permissions to do so and would like to know if I am able to switch my accounts through the app to store the payment info through Google Play. I am using an Android device and both accounts are through Gmail.
After trying out a few different solutions to this, I found that it is not on the app's side, but rather an issue with Google Play. Uninstalling the app completely and downloading it through the website (the app does not work I've found) under the other account will transfer it successfully, and this should work for all Google Play Games. Here is the website I found the solution from should anyone have the same issue. Happy Hunting!!!