I would hope that they can cooperate. Like you said, pretty vague, but it could work.
Eliminate many of the loopholes so that businesses are on a more-equal footing with each other. Also, lowering and fixing the tax rate could, if done properly, encourage companies to stay at home instead of going abroad. No, it won't encourage Nike to stop making shoes in 3rd-world countries. But, it could entice companies to stop using offshore tax havens and corporate schemes.