But it is RetroActive, keyword. Besides, if a game bombs and is no longer being published after 2 months you think it should be eligible? I'm sorry, but I don't think recent games should not even be considered for the feature.
Assuming they do intend to go through with DS, I will stick with the spirit of RetroActive and nominate only early DS games:
Advance Wars: Dual Strike - Great strategy game, I really loved the matches that took place on both screens. If you have one of the GBA games, you can buy additional maps in the Shop.
Kirby Canvas Curse - First game to really take advantage of the touchscreen and a real departure for the series.
Mario Kart DS - Many people consider this the best Mario Kart ever, and for good reason. The only complaint I have is that online play became crap due to the screw-up Nintendo made called snaking, if you weren't snaking too you had zero chance of winning.
Nintendogs (any version) - I think it's safe to say that this is the game that finally helped the DS pull ahead of the PSP and stay there, this game was the system seller for awhile because people love having a pretty realistic looking dog to take care of and play with.
Super Mario 64 DS - Yes the base game is no stranger, but the DS one had a lot of changes (like three new playable characters, the different powers, levels having different star objectives, etc.). The main issue many people have is that the game does not control as well as the original due to the lack of a analog stick.