Scizor is probably the best revenge killer i know of, with bullet punch and U-turn, its also a Scout other than ditto. Scizor is OU where as Ditto is OU in DW only.
Choice Scarf Tyranitar is also good at revenge killing(Along with a ton of other Scarfers with high attack/special attack such as Chandelure).
My Final Choice is Infernape with its high speed and powerful attacks, it can usually finish off pokemon.
