Clefairy and Clefable share an attack called Metronome.
Clefairy's reads:
Choose 1 of the Defending Pokémon's attacks. Metronome copies that attack except for its Energy costs and anything else required in order to use that attack, such as discarding Energy cards. No matter what the type the Defending Pokémon is, Clefairy's type is still Colorless.)
Clefable's is more of the same.
We have to make a distinction in what's considered a "requirement". That is, what "anything else required in order to use th[is] attack" includes and
does not include.
The game I played where I was stalling away with my Chansey turned out to be a bit of a nightmare when the Defending Clefable was starting to dish out 80 damage (via Metronome → Double-Edge) with no repercussion. No recoil.
Here's the thing: Chansey's Double-Edge attack reads like this:
Chansey does 80 damage to itself.
Meaning,
as a result of using this attack, it does 80 damage to itself. It isn't like Energy cost, where you must have four of any Energy attached to Chansey
in order to use the attack. It only happens when you
do use the attack.
Stuff like "Discard 1 Fire Energy card attached to Charmander in order to use this attack" is ignored, because it's a cost. The description of Metronome states that it ignores all "costs", or "requirements".
It does not, however, say anything about ignoring that which occurs
as a result of using the attack. This means (courtesy of the Player's Guide):
- Copying Double-Edge, or any other move with recoil, will also do the specified amount of recoil to Clefairy/Clefable.
- Copying Water Gun or Hydro Pump will also copy extra Water Energy on Clefairy/Clefable.
- Copying Leech Seed or Leech Life will remove damage counters from Clefairy/Clefable.
- Copying any attack that requires coin-flipping will still require coin-flipping.
- Copying Dream Eater will still require the Defending Pokémon to be Asleep.
The following are costs that Metronome
ignores:
- Copying Zapdos's Thunderbolt does not require discarding any Energy cards.
There's a truckload of other things, as well. Interesting (and frustrating) exceptions include dealing with Dark Flareon's Playing with Fire attack. I'm not sure how that one would work (as a
result, the attack does 20 extra damage upon flipping heads, but in order to use the attack at all, you must have a Fire Energy card to
discard,
also as a result of flipping heads—or would that just be a thinly veiled "requirement"?).
The most daunting thing about this is that (and I don't claim to know anything about programming or how it works, but) you'll have to make an exception for
every single Pokémon that has an attack with a "result", rather than a "requirement", for every single future set, as well as the ones that have been released already, in order for the attack to behave properly.
