Ditto

While Ditto spent the last four generations of Pokemon shunned in the corner of Bill's PC Box, only brought out to breed with other Pokemon, Dream World granted it a new lease on life. With Imposter, Ditto copies any stat boosts, moves, abilities, and even the species of the opposing Pokemon itself! Ditto works as a fantastic revenge killer thanks to its ability to both annihilate threats with the immense Speed granted by a Choice Scarf and take advantage of the opponent's boosts. This also makes the opponent wary of setting up early in a match, as the opponent does not want to get demolished by his own sweeper. However, Ditto is not without flaws. Its checks and counters completely depend upon what it changes into, limiting Ditto's staying power. Our little pink blob should never be underestimated, though, as one wrong move can spell impending doom.