Yo Pojo, I'm here to compare two cards which have the same purpose - to mimic and to copy!!!
Let's start with Ditto, I love this guy. His ability to copy anyone and eliminate advantages is just awesome. Combine this blob with ER/SER to leave the defending pokemon stranded and vulnerable to it's own high damage inflicting attacks!
   Where as Clefable has the same concept, with potential to go further, it's weakness to Fighting is not covered up by it's resistance to Psychic and leaves it vulnerable to Haymaker. For one energy, however, it can copy any attack. Can you say 'Speed Kills' ? This guy will absolutely murder just about any 2nd stager if combined with GOW, which brings out the pokemon that is yet to have any energy on it. On the contrary to Ditto, this guy builds himself an advantage.
Ditto
Props
No advantages
Can use any energy for an attack
Energy Removal leaves the defending pokemon helpless
Can duplicate pokemon powers
 
Slops
Benching this dude will most probably kill it
If it gets attacked and then the defending pokemon activates a pokemon with a low hp it's dead meat
Energy Removal will leave it helpless
 
Clefable
Props
Low, and I mean Low cost attacks
Combine with GOW for easy kills
Pokemon such as Ninetales, Base set Zapdos and Moltres don't even get a look in against him
Very Fast
Don't need to flip to attack, will do it automatically
 
Slops
Clefairy is awful! Hitmonchan will murder it hands down
Hp isn't too impressive
weakness to fighting
Really depends on whether or not you get to attack first  which gets you the real advantage
 
Thanks for listening,
All e-mails to be sent to russian_rey7@hotmail.com
Rey