Update to the rules, sorry if it was not clear.
You must use the weather inducing ability on your specified Pokemon (example: If you have Sun, you must use Drought Ninetales, you can't use Flash Fire Ninetales). You can also not use another Pokemon on your team with a weather inducing ability but you can use the other ability of that Pokemon (example: If you have Sun, you cannot use a Sand Stream Tyranitar on your team but you can use a Unnerve Tyranitar. Keeping in mind, you have to use Drought Ninetales). Hope this clears things up, as the theme of the tournament is Weather Wars.