Forum rules: Do not post bugs or feature requests here! Report bugs to our Issue Tracker and suggestions to Suggest a Feature.

This site is not for solicitation of services or 'purchasing' development. Please do not post requesting side mods/plugins and so on. Your thread will be removed, and you will receive a warning.

By Megit
#152680 Use a "Trainer Editor" and place the trainers yourself, those will be permanent.
The ones you seem to be refering to are trainers that spawn like any other Pixelmon, and therefore has a despawn timer.

You get the editor using the Creative menu.