Yanmega

Blessed with two great abilities in Speed Boost and Tinted Lens, Yanmega initially seems like a great choice for either a special wallbreaker or a cleaner. However, Yanmega's lack of power and mediocre STAB combination means that it often falls short in practice. In addition, a terrible Stealth Rock weakness and vulnerability to any form of priority makes it very difficult for Yanmega to perform either role. Yanmega's inability to break through common special walls such as Florges and Blissey makes other Pokemon like Infernape or Kyurem better wallbreakers, and better options for late-game cleaners Mega Sharpedo, Lucario, and various Choice Scarf users.