It's pure speculation, but Salazzle might work. Access to Fake Out, Fire STAB, and a higher speed tier gives it the edge in most situations, and it can run Taunt or Encore for more lead utility (although it has trouble fitting all the moves it wants in one set). From what I seen, Focus Sash sets are the most common due to its low bulk.
I like that idea though, but can't Kartana outspeed it? I might replace Tapu Koko with Celesteela as it can counter most of my weaknesses and wall opponents (And give me immunity to ground type moves). Do you think that'll be a good idea?
Celesteela will have Flamethrower, Heavy Slam, Protect, and leech seed with 210 Hp/44 Atk/128 Def/ 128 SpD