Most likely, when ToSBase datamines things, and adds it to the database, they use a script/function/program/whatever have you. It probably creates attribute pages based on the datamined classes, GM being one of them, so it was automatically created.
But we could just ask @Flash.
Hey @FatePGN do you think there is an application to register as a GM.Not like I would like to but Iām just curious.
IMCGames is based in Korea, and if they are hiring, it would be an office job in Korea. Iām pretty sure they have a hiring page, but I donāt know if they are, or where to go to apply sorry. Your best bet if you seriously want to do this, and do actually live in Korea, and speak Korean, is to send in a support email for more information.
Remember, ToSBase is only a fansite and doesnāt have to be 100% correct
@Flash (the author of tosbase) could also creates a āDuckā class and make it appears in the class list with no attributes if he wants to.
Im joking but the GM attribute page exists for the exact same reason that Iāve mentionned before : Flash didnāt want to write a if (isGM) { dontDisplayInTheList() }
LMAOā¦the duck 
So many mentions 
When I noticed that GMs (yes those are the Game Masters ;)) have their own class I thought about removing them from the list but decided against it as I thought it was quite interesting to see their skills. All pages that allow you to search for a class use a auto generated list so when a new class is added I donāt need to add it to many different pages manually. Because of this the GM is also listed in the Attribute Database even though there are no Attributes for it 