There is no platinum server, its Diamond and Pearl, and the beta passes dont go on sell until 3pm EST on August 25th. I believe at that time they will be available on our shop here: https://store.mc-complex.com/ or via a link in our discord.
As FroggeeDuck said, there is no Platinum server; however, our new Diamond and Pearl servers have just recently opened, so feel free to check out and experience a whole new Pixelmon adventure! If you have any questions, please feel free to DM me! Hope you and your loved ones are staying safe and healthy.