Your Extra Deck should consist of Xyz, Synchro, Fusion, or Link Monsters that complement your Main Deck strategy, while your Side Deck should contain cards that can counter specific threats or strategies you might face in a match
If you use anything but Teferis Protection, youre going to be left without blockers
Avacyn, Angel of Hope Avacyn, Angel of Hope doesnt end games instantly, but it enables some of the most punishing board states imaginable
Theyre a useful guidepost though, so keep them in mind early if youre unsure which lane to take
If you're looking at a stack of bulk cards and trying to figure out your next move, start by pulling out the valuable singles using a scanner app, then decide whether you want quick money (sell everything to a bulk buyer) or maximum money (sort and sell strategically)
Sabrina is invaluable against this deck, as you can force your opponent to put Gardevoir in the Active position, rendering its ability nearly useless