Another question Darkrai Endless darkness

[nahuelarce]

Suppose I use endless darkness on the defending pokemon and between turns he or she flips one heads and one tails.Then, when my new turn starts, the defending pokemon is still asleep but I want to retreat Darkrai LV X with one of my benched pokemon, the question is: how many coins is my opponent supposed to flip? One or two ?
Thank you

 

[PokePop]

Still two.
The effect resides on their Pokemon.