Goreclaw's last ability affects only creatures you control with the appropriate power at the time it resolves
Many of the attack names in the TCG are either directly pulled from the mainline games, or are clever references to the Pokmon and their abilities
This decks mana base is built with this in mind, including pain lands like Adarkar Wastes which can tap for two colors and be colorless
While Mega Darkrai ex may not be topping any regionals anytime soon, its going to be massively popular more casually, and especially on Pokmon TCG Live
This kind of card would slot well into the latter, so you'd just be looking at another flavor of Affinity decks popping up and wreaking havoc once more
Disadvantage : Shaymin only has a 30-damage attack that requires two Energy of any color, so its mediocrity as an attacker reinforces its role as a support Pokmon