Luna has always been the main host of Practical Lunacy; I mean, her name is LITERALLY part of the show's name. Luna has been the only constant since the show started. There has only ever been a single episode that she wasn't in; and it was not pretty.
There have been lots of other hosts in the show. The most notable of them being: Mikal (the original PL co-host), Scott and Schuyler (the owners of the station PL premiered on), Melissa (a fan favourite), Triggar (who was involved off and on from when the show started in 2003 until is passing in 2023), Sarok (who was a host off and on for a few years), and Daniel (Luna's husband of eleven years, and the longest running co-host of the show from 2010 until his passing in 2023).

All that said, the current era of the show (which Luna has dubbed as season 20, but maybe we should pull a Doctor Who and call it season 1 because of all of the rebranding) has three main hosts: Luna, Baron, and Nixie. Luna, as always, is there for each show, and is joined by Baron for every show and Nixie on Fridays (although she can join in and may pop up during any episode for surprises!). You can learn more about the hosts by clicking on their names below: