OK, this is a card that many people have heard of and are scared of, but
hesitate to put one in their deck. It's Clefable. This is why Clefable (and
Clefairy) are a valuable addition to ANY deck:

Clefairy:

ok, clefairy, we all have to admit, sucks <stinks> . 40 hp. dead in 2-3 turns
usually, definitely not enough time to load him up for metronome. its other
attack, sing, is crappy as well: 1/4th chance that the defending pokemon
stays asleep when he could attack, then you factor in evolving, benching,
full heal, devolution spray... either put clefairy on the bench until you get
the almighty clefable, or use it simply as a decoy: dont even put the energy
on it for sing.

Clefable:

ok, this is the reason you even think about clefairy. clefable's metronome.
first the stats: 70 hp, 2 retreat (there is a mistake on the new apprentice
patch) weakness: fighting. resistance: psychic. stage 1, from clefairy. now,
his attacks. metronome. for one colorless energy, you can copy any one of the
opponents attacks, and you dont even have to pay its costs. then, minimize, i
have never seen it used, costs 2 energy, could be used to stall. ok, back to
metronome.

metronome is, in my opinion, one of the best attacks (when it only costs 1)
if you don't know what it does, look at a spoiler for the official attack.
here is the basic move: clefable picks an attack that the defending pokemon
has. clefable uses that attack against the defending pokemon, without any
costs. now, a lot of people lovvvve ditto. well, yes, he is a basic, but the
reasons for getting clefable after a few turns instead of ditto right away is
countless. ditto still needs the required amount of eneergy for attacks;
clefable doesnt, which means while ditto is powering up so is the defending
poke, and when they are both ready ditto is already hurt. clefable can be
brought from the bench right away and begin attacking the pokemon. ditto is
very unstable. my favorite move is when i have a pokemon active with the
defending poke ditto, which has some damage but not enough to KO it. then
benching my active, and bringing out a poke that forces ditto to die because
of counters exceeding hp. and i havent even attacked yet. clefable doesnt
need to worry about that. also, clefable has 70 hp, so it can afford a few
licks. finally, one of the greatest moves i have ever seen (i was the
victim). i had a benched zapdos with an electabuzz to stall. i knew if i
could load up zapdos, i would win. well, my opponent whips out clefable,
retreats, GOWs my zapdos, and bam, uses thunderbolt, and his clefable only
had 1 energy. and he didnt even have to discard either, because metronomoe
doesnt encompass costs. (i lost that game). also, i had an undamaged
articuno, my opponent whipped out a clefable and i neevr even got a chance to
attack it. he killed me in 2 turns with 1/4th of the energy i had attached to
my 'cuno. grrrrr. there are some weakness, for example, fighting against,
say, a magikarp, but(back to icky ditto who would be dead) you have 40 more
hp than it does, and if gyarados comes out, baboom while it is loading up for
rage you can attack right away, and all this time be loading up your benched
poke's with energy. oh, and another bad situation is clefable vs. clefable,
but ditto is in the same shape as well. just hope the other guy has less
cards in his deck so he retreats.  ok/ heres how to add this amazing card to
your deck


take out energy, some weaker pokemon, or some trainers. clefairy/clefable
works even if there is only 1 of each in your deck. i reccomend 2 clefairy, 2
clefable, or just 1 if you are conservative. trust me, they rule against
gaymakers (even against hitmonchan, even with weakness) and your opponent
will cringe when he sees it.