Kecleon

Kecleon is one of several Pokemon introduced in the third generation with a gimmicky ability that heavily influences their competitive value. Color Change takes what would have been just another underpowered Normal-type with a nice movepool and turns it into something unique; combined with its excellent Special Defense, Kecleon makes a great counter to Choiced special attackers or those with limited coverage. The cost is quite high, however, as opposing Pokemon with good coverage can easily take advantage of Color Change. Furthermore, its frequent type-changing prevents Kecleon from having a consistent STAB attack to rely on. Constant prediction is required in order to get the most out of Kecleon, but when used well, it can be a valuable asset indeed.