The elements of harmony are infact not the mane six!

Trixie replaces Twilight as the Princesses Student but Celestia isn't the Princess (You could have guessed that.)

Hunter an earth pony gifted in the ability to survive in the forest and take care of the creatures there first hand she replaces Fluttershy as the element of Kindness.

Courier is a package delivery expert and a part time inventor he replaces Applejack as the element of Honesty.

Lightning Dust replaces Rainbow Dash as the element of Loyalty.

Fiery Forge is the a master smith and the forge master in Ponyville she will be replacing Rarity as the Element of Generosity.

Pinkie will be remaining as the Element of Laughter.