While there are two different Mega Pokemon ex in this deck Mega Sharpedo ex and Mega Gengar ex they both work so well together the strongest version of this deck is likely to be a combo of the two
This time, instead of one shared deck, around 20 testers got their own 60-card decks
Do all Walls have Defender
"Zombie World" in the Field Zone cannot be destroyed by card effects, also neither player can target it with card effects
While black still sometimes features above-rate creatures with downsides in its wheelhouse, this card is all upside
Another possibility is Desert Sunlight , but that's basically calling off the Battle Phase, so it's not quite as nice (unless you have something like Elemental HERO Rampart Blaster or Total Defense Shogun, which can attack in Defense mode, but what are the chances?)