N's Rhyperior
Aspiring Trainer
Quick Ball and Training Court will be rotated once we get these cards. Marnie and some other cards like Switch will be likely to be rotated as well.Well, if I understood it correctly, you can switch between different Clefairys to use the ability multiple times in a turn, up to a maximum of 4. Even with just three uses and one manual attachment that's 10x20, 200 damage in one go, all while emptying your deck of energies so it's easier to draw more useful cards with Bibarel. That plus Choice Belt is a 1HKO on evolvings Vs, and since you're playing basics you can do it going second.
4 Clefairy, 3-3 Bibarel, 1 Manaphy, maybe 12-14 energies, and the rest of the deck can be filled with useful cards like switches, air ballons, belts, exp. share, Boss, Marnie, Peonia, Training Court...
EDIT: Oh, and of course 4 Quick Ball and 4 Level Ball to get those Clefairys as early as possible. Maybe it is really too resource dependent.
Like what I said, Clefairy is just bad as an atkr. 20x is just outdated in the meta these days. I prefer 30x or 40x to get significant numbers by using minimum effort.