Aromatic Mist
Sensuble
I'm hoping for Fairy/Dark or Fairy/Ghost
Even as a huge fairy fan, I hope this isn't the case. We've already got Magearna and most likely all four island Guardians, another fairy legend would be overkill. Especially since that'd give Fairy over seven legends in two gens/three years, compared to zero for Poison which has been around for seven gens/20 years.
As for Ghost/Fairy, if Tapu Koko and Pom-pom Oricorio are any indication, the 'Poni' Island Guardian may be Ghost/Fairy.