Okay, I got the info from the rulebook. There are five categories, and you have to compete in at least four of them.
Category 1 - Western Pleasure and English Pleasure
Category 2 - Showmanship at Halter, Western Horsemanship, and Trail Class
Category 3 - Reining, Western Riding, and Versatility Ranch Cutting
Category 4 - Hunter over Fences, Hunter Hack, and Pleasure Driving
Category 5 - Barrel Race, Stake Race, and Pole Bending
I'd like to do them all if I have the time, but if I don't I think I'll give Category 4 a skip, since HoF and Pleasure Driving will probably be the hardest to teach her.
And I have the score sheets, so you can get an idea of what they want to see in each of the classes: Missouri Fox Trotting Horse Breed Association - Versatility Judges Score Sheets
From the first list, I think the "ranch" classes are for a separate award - WGC Ranch Horse as opposed to WGC Versatility.