Its a shame that there aren't any tournaments. I'd love to test my monsters on real opponents. I know that MR Online is coming soon as well as the DS release but its not the same as playing in a place for events like other games. Monster Rancher has been left by the wayside. Maybe someday :c
What I've noticed is that in order to get tournaments started with any game, you must bulid a strong competitive community around the game. Not only on your personal message board but here as well. Make sure that you invite follow Monster Rancher lovers to this website and start making efforts to start your own thing. You just need to be willing to travel in order for this to happen.
The next WiFi Tournament takes place in Dry Dry Ruins. Players must use Mushroom Boosts wisely in this standard style race. Takes turns sharply, boost off ramps and power slide like crazy to get your best overall time.