Any extreme primal (minus Levi) is good. While most primals can be single tanked, if you join a pony farm group and just state that you'd like to do tank swaps, you'd probably find people willing to do that.

The actual "mechanics" of a tank swap are pretty easy. Switch to shield oath. Queue up Halone combo. Hit provoke then Halone/Scorn. Done. The harder part is knowing when to expect the swap. Since "best practice" might want you to have halone queued up, that means you have to time things. Switch to shield oath about 5s before the swap. Get up to Halone combo. Then do the swap. Of course, you can hold the halone for a few seconds before it expires.