Ninja Gaiden DS was just one of a number of DS titles announced by Tecmo in the latest issue of Japan's Weekly Famitsu. The publisher also shared first details on an all new DS entry in the Monster Rancher series.
Tecmo is using putting the DS to full use, primarily in how you go about creating your new friends. You can use the stylus to draw patterns, which are then converted into monsters. You can shout thing into the microphone to create another set of monsters. Or, if you still have Game Boy Advance carts about, these can be inserted into the Game Boy Advance cartridge slot for even more monsters; this takes the place of the CDs that were used to generate monsters in previous Monster Rancher games.
Once you've created a monster, you have a number of ways to train it. New to the DS version is a board game which you can play to raise your monster. Alternatively, you can select training options the old fashioned way, from a menu. Eventually, you'll be able to merge multiple monsters into a super monster and beign climbing the ranks of a monster tournament.