Simple Percy Jackson demigod Randomiser

Hey

I am making a Percy Jackson themed server, using pex among other plugins.
In the books, demigods eventually know which god is their parent.
I need a plugin that lets me randomly sort players into a pex group.
It needs to have the option to make a list of which groups players can be sorted into by typing the command. (So it doesn't sort someone to, say, Admin)
It should also make it so you can type the percent chance you will get into that group.
Group: Zeus
Chance: 2%
I want it to be so you can edit the group ands everything with PermissionsEx.
Command: /sort (player)
^ This way when a player steps on a p plate above a command block they get sorted. This command should only be available for ops and command blocks.
Thanks for reading, hope you can help,
Sidewalk
(ps. Players will get their demigod skills with permissions. This has nothing to do with this plugin, I will do all that with PEX)

Also, it should only be able to run on each player once. (So they cant switch groups)

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

This isnt very "simple"

 

Simple in its name, its gotta be cmon

 

@Twisted_Panda @SuperSniper
It doensnt have to directly hook into pex, it could just say in the config make you list the commands you want to randomize with command.

 

Couldn't you do this with dispenser randomizers and command blocks?

 

But then how could I stop players from doing it again if they don't get the ne they want?

 

Make a scoreboard team of players who have been sorted