Re: Where do they have Aikido Tournaments?
You will find none because there aren't any. Aikdo is the way of harmony. For that reason, and based on the teachings of O'Sensei, founder of Aikido, we do not have tournaments of any kind.
NOW... I think there MIGHT be one branch that broke away from the rest of aikido in Japan and there may be tournaments there. But that is based on speculation and if it were true, would still be against the teachings of the founder.
If you're looking for a tournament to participate in, try another art. If you're looking to learn a new skill, attend the Seminars given all year long by various Shihan and high level instructors.