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Skarmory can use almost any item in OU. The only item ban in OU, to my knowledge, is the Soul Dew, as it causes Latias and Latios to have stats which are too high to be acceptable in standard play. There is also an on-site analysis for Custap Skarmory. http://www.smogon.com/bw/pokemon/skarmory/uber#Custap_Lead