How does Clefairys Metronome attack work?
Imagine that there’s a copy of one of the Defending Pokmon’s attacks written where Metronome is written, so that Clefairy is doing that other attack. The only differences are that Clefairy pays instead of whatever the original cost was, and if there are any special things required in order to use that attack (like discarding Energy cards), Clefairy doesn’t do them.