So I'm working on the method of progression.

I'm thinking that each tree is based on the Elements of Harmony, so I'm thinking that levels are tracked based on the Elements. so Characters are classified by their race, and their base element (eg. Unicorn Kindness, Pegasus Loyalty) their level is determined by the highest level Element on your ponies elemental roster. So if your a Pegasus with 4 levels in Kindness, but 8 levels in Honesty, your character would be classified as Pegasus Honesty level 8.