Let's get Pixelmon installed!
With that out of the way, there are a few ways to get Pixelmon running. I would recommend the use of a modpack launcher!
Download link for Technic Launcher: https://www.technicpack.net/download
Download Link for ATLauncher: https://atlauncher.com/downloads
Download link for GDLauncher: https://gdevs.io/#downloadContainer
I would personally recommend GDLauncher as it will auto-install the correct Java for you as well as manage your Pixelmon install!
Remember to add the Pixelmon Reforged Modpack!
Once you load it up, add our server IP: play.pokehills.com
Make sure to load our Resource PokePack to be able to see some of our Special Pokemon!