It says on the card: whenever your opponent flips a coin DURING HIS OR HER TURN.
This has nothing with sleep conditions. You flip your coin between turns.
Mostly, rosarade could work, by confusing the defending pokemon, but they still can retreat. There is actually nothing that will prevent retreating. There are some pokemon, Dugtrio, that can give 20 damage if they retreat, but I think that is it.
Just a thought, as shiftry is in the game Grass and Dark, you can use it with the new prime: Yanmega. As you are using Giratina Let loose (???), judge and copycat, so...