i was in a random battle and i found that nuzzle didn't trigger iron barbs or rocky helmet despite being a contact move
here is a paste log starting the turn both pokemon entered the field and ends when another contact move triggers both item and ability
http://pastebin.com/JrLCPCZM
here is a paste log starting the turn both pokemon entered the field and ends when another contact move triggers both item and ability
http://pastebin.com/JrLCPCZM