"I'm in a better clan than you"
>is in darklords
Reporting won't do anything. Him calling his clan to report you won't do anything either.
Taking templates is not against the ToS.
Even if he somehow makes his inactive trollfest that is the Darklords mass report you, he won't get anywhere, for you didn't break the ToS either.
If you really are irritated your only option is to ruin his game, though this'll only piss him even more and get nowhere :P That, or you can invite him to a 1v1, wreck his arse up (if need be, ask some of your clanmates for guidance, they can beat most dorklords easily), and then make fun of him. Realistically, the best you can do to him is mocking back.
Either way, the best suggestion I can give to you is NOT PLAY OPEN DIPLOMACIES. They exist to be ruined by trolls and boots, hosted by complete shmucks most of the time. Call in clanmates, friends or other clan members for your own games.