Pixelmon Mod

I was wondering if you were allowed to have a unwhitelisted server and having server donations that were used to fund the server. If someone could reply quickly that would be fantastic! Thank you for your time!

Well, look in the server section, most are that way.
No whitelist, so anyone can join, and hop in on the adventure.
And they propose donations, and as the name implies, noone is forced to donate.
And they use these donations to make the server grow, or fund back the mod itself (MrM) when the donations overflow(?)
Hope this is enough, have a nice day.

Thanks much am I allowed to advertise on the server forums page?

You can go there and create a thread for your server, yeah.
A bunch of servers are there already, so competition is going full throttle haha.
That's why I'm sticking to playing those server, hehe.