-Have the following: two or more Nintendo DS systems and one Metroid Prime Hunters game. Have the DS systems without the game in download play mode. Make sure the host wins the game so the star rank on the Hunter's license matters. You will get one ranking point if you win in a two player round, whereas if three players play, you will get two ranking points. If you play Wi-Fi mode and the other players' ranks are higher than yours, be careful since they may be better than you. Their star rank is relevant in terms of how many points you get.
-Keep challenging a friend while the game is on 1 score point. Repeatedly win and you will be a Legendary Hunter quickly.