And Princess Cadence and/or Shining Armor as Heart.  
GO PLAN–oh wait, wrong series.

Swap Rarity and Twilight and this chart is perfect.
 
Though I’d have pegged Fluttershy as an Airbender, too…

I thought rainbow would be a firebender and twilight would be the avatar

I’m pretty sure Pinkie is a chi blocker, I mean come on you know she and Ty Lee would get on like a house on fire.

The charts don’t work like that.

As regards to RD’s strength and rashness, the airbenders as depicted in ATLA (Haven’t seen Korra yet) are all monks. They are going to be peaceful, and not particularly strong, because of that. One does not necessarily have to be a monk to be an airbender.

FS: Non-bender  
RD: Airbender, she can feasibly achieve everything she’s done through manipulation of the air (clouds and movement thereof by changing air pressures, lightning by micromanagement of winds to create turbulant friction in the clouds)  
RA: Water (Pretty much default)  
AJ: Earth (Duh, fits the bill perfectly)  
Twi: Avatar (Through magic, she could conceivable achieve all the effects of the other four, AND counter them)  
PP: Fire (Fire is chaotic, and she’s certainly got a lot of pep)

Firelord Ozai,Azula and the General from the first season could be the only firebenders who were evil during the course of Avatar:The LastAirbender. At least how I saw it.

so who is heart?

don’t know how ponies would translate to that universe since any adequately weather trained pegasus could technically manipulate all elements…and dash definitely fits the mentality of a fire bender

Ok I admit that was harsh but I don’t see waterbenders mugging people in the streets.

I’m relating them to the bending arts, not the nations. As for Celestia, she could be a previous incarnation of the Avatar, and Spike is a dragon.

Fanguy, they are not, not all of them, in the Legend of Korra they are a normal race ……

@randomfanguy:  
 
excuse me, what you just said?

Seems ok. Twilight as a firebender seems a little iffy considering they’re evil.

And what about Spike?

That was to RIG.

I’d have done that, but Rainbow can make tornadoes (airbending), rain (waterbending) and lightning (somehow related to firebending), and she’s strong (earthbending). Also to have an equal amount of benders.

Celly should be the avatar, you know with the horn, wings and bigger then any other pony…

….  
Twilight should be the Avatar…