I built a Gen 7 OU Team around def Cresselia w/ flame orb
rest, sleep talk, psycho shift, moonblast... and yes you can pass sleep WHILE asleep :]
(I thought of it to let me help vs Mega Mawile originally- but I figured id run up to Adamant Ttar (and the speed creeped Rotom-W by one point)
https://pokepast.es/12f8079f1175894a