I'm trying for this using Night/Water:
1st attempt - Neo Bubble
2nd attempt - Neo Bubble
3rd attempt - 12 hours (spent 2 gold to speed breed; turned out to be iridescent)
4th attempt - Coral (spent 6 gold to speed breed)
5th attempt - 12 hours (turns out to be mistmoth)
6th attempt onwards (I lost track) - all were either Neo Bubbles or Corals.