Well, I wasn't going to enter, but it turns out I did come up with something after all, so I'll join in image.
I wanted to do something about weight, but when I found the pokemon, I had...
other ideas. Funner ideas.
The ability, admittedly, could use some more work, or at least a clause that it doesn't work if Kartana is knocked out, but it's probably not so bad; the idea being that since the only reliable way you have to do damage is by keeping it in play, you have opportunities to remove it temporarily from play, but preventing it from being out for good, which plays nicely with the slow damage of the paper cuts; if you're going to the deck, then back, then again to the deck and so on, the knocking out of pokemon is slow and drawn out, but inevitable. Plus, since there's a limit to how many you can have on your deck, it makes sense to try to keep this one alive, if not in the field, as much as possible. I'm sure there's a way to give nuance to the ability, the only question is if it can work with the space limitations.
Coup de grâce is just what it says on the tin; once you weaken something enough, then you sweep it out; that's why I left the damage low; I wanted everything to work around the same strategy; gimmicky, yes, maybe not too competitive (and if it is, it is by being overpowered), but, it has a charm that is sorely lacking in more straightforward pokemon.
And the star of the show, the Nick counter; I know, I already did counters with primarina, but I liked the concept of the death of a thousand paper cuts, so I tried to put it in the game the best way I could; poison damage was an obvious starting point, and what does poison damage use? counters. Beyond that, the attack is fairly basic; a kind of poison-like special condition that never leaves and only does damage as long as Kartana is in play (to get synergy with Fold, which was my first idea for it).
Putting four counters seemed too much, but considering I only get one Kartana per deck (plus the waiting to draw it back if I use Fold), I think it could be fine. Maybe 3, but 2 would be too little; like with my Primarina, scaling power for attacks that damage based on counters is very tricky.
I'm thinking now that maybe I would do well in reducing TPC's cost (and amount of counters), since I'm leaving Kartana without a way to actually damage pokemon with such an onerous cost (considering Coup de grâce doesn't do anything most of the time). But then again, it's very likely it'll never see the discard pile anyway, at times you only need it in play, not attacking, and discarding energies is an acceptable sacrifice in exchange for keeping it alive, since it reduces its ability to draw power from the deck without sapping it from other pokemon who might use it to actually do damage. Maybe the high cost (and high energy loss if you Fold) is a good way to balance it a bit more and prevent it from just flooding everything with counters and Coup de grâce-ing everything as it comes weakened.
My only regret is that I don't take advantage of the UB rule, but, with my Pheromosas I didn't either, so I don't mind that much; a unique concept always goes before trying to shoehorn use of a generic power.