Game Changers are not allowed in Brackets 12, limited to 3 per deck in Bracket 3, and unrestricted in Brackets 45
Maybe people are thinking about running it in some sort of Aromatisse (XY 93/146) deck, where you have the versatility of other attackers that you can run and move your energy around and heal Giratina and preserve your energy
The enjoyment (or frustration, if you're unlucky) you'll get out of Perfect Order completely depends on your enjoyment of the chases and various commons you can pull
Black-green is one of my favorite color combos to begin with, and Eldraine is full of fun cards like Bake into a Pie, a black instant that destroys a target creature and bakes them into a Food token, Sweeney Todd-style
Card Type / HP / Stage: Dragon / 240 / Basic
The haste-matters decks like Minsc & Boo, Timeless Heroes and Ognis, the Dragon's Lash havent adopted it as an auto-inclusion yet, so that tells you something