The new DS version will keep this tradition intact, but with some differences. Players will speak into the microphone, draw on the DS screens, and even use GBA carts to generate new monsters.
The new trailer presents this and more:
Monster Rancher arrives on the DS in March 2010.
I wonder if they could incorporate the DSi's ability to not freak out when you remove a cart, and let you use other DS games for monsters? Or even let you pull songs from the SD card for monsters. Somehow use the wireless functions to produce monsters from wi-fi signals?