I don’t watch Leno or Conan hardly at all (did many years ago). But I think the sidekick position is a good one. Conan had Andy Ritcher before he left.
Leno’s band leader Kevin Eubancks was essentially more of a sidekick than a band leader, Letterman uses the band leader with the sunglasses as well.
I like watching the reruns of Larry Sanders (Garry Shandling). Jeffrey Tambor’s sidekick character of Hank “Hey Now” Kingsley is a treasure. Rip Torn is a hoot as well as the producer.