Details: One of the ten possible challengers you will face as you sit on the Champion's Chair in the Champion's Hall after defeating the Elite Four is Former Team Skull Admin Plumeria. She's no longer a Team Skull Member, and was convinced by Nanu and Molyane to challenge the Elite Four. She specializes in Poison Type Pokemon.
Challenger Plumeria - Level 61 Gengar, Level 61 Muk, Level 61 Crobat, Level 61 Toxapex, Level 61 Salazzle w/Poisonium Z