There aren't any clear answers for dealing with the Pokémon TCG Pocket Cresselia ex Drop event, thanks in part to the limited capabilities of Darkness-type cards, but we do have

A ONE Esports guide to the Cresselia EX drop event in Pokemon TCG Pocket including all event promo cards, solo battles, and event window.

Here’s how to make the most of Pokemon TCG Pocket’s Cresselia ex promo card!