Before I go on with a whole bunch of Pokemon: Avatar ideas, I need to explain the essential origin story.
After TLOK, Korra is pulled into the Spirit World.
There, the entire Avatar lineage explains the current situation: an illness has spread to the people of the world and it is up to her to purge it.
The illness feeds on ki, and once it leaves dormancy, it can and will wipe out all of humanity, except for the Avatar.
In order to fix it, they instruct her to create new bending arts or expand existing ones (hence the 17 types of Pokemon), allow everyone to learn two bending arts by distributing the power of the Avatar (hence dual typing), and to completely restart the population.
Of course, all of this requires a tremendous amount of power and they place her into a status of permanent avatar state.
Upon her return from the spirit world, korra is understandably disturbed and conflicted: she doesn't want to lose her loved ones but either way, they have to go. Not wanting to appear evil to the people, she disappears completely from society and becomes a recluse.
She dons a long white cloak and a shielded mask (think fencing mask) and takes on the name "Arceus". Over the next few months, Arceus, the mysterious benefactor, invites the leader of multiple groups and societies to visit him in his mountain domain. There, he teaches them the new bending arts, telling them to spread it as far and wide as they can.
Next, Arceus sends a ripple throughout the world, relinquishing her avatar powers to give people the ability to dual type. Her final step had a large obstacle: she used up most of her power in the second step already, leaving her incapable of simply resetting. To solve this problem, she put the rest of her power into three orbs: the adamant orb, the lustrous orb, and the griseous orb.
[Cont.]
