You basically have to be on either end for leagues. Memphis or Sevierville. Chattanooga still runs a small league. Nashville is trying to be revived with a few PRs.
If you are in Nashville area, Go to Next LEvel Games in the Bellevue Mall and let them know you are interested in a Pokemon league. They are in the process of starting one there. The more who talk to them, the faster things will go.
We are also having a prerelease there on Sunday Nov 5 and a City Championship on January 6th
Next Level is great and very open to doing the league. I ran it there for about 6 weeks and had TONS of interest (I gave away about 4 boxes of theme decks). Sadly, I left Nashville and wasn't able to continue. But, point being, its a good location.