I guess I'll do the same.
1) Front Mission - The mecha alternate to FFT, it's the only "tactics" style game I've ever liked. The SNES version is one of my favorite games of all time, but knowing you, you've already played it.
2) New Super Mario Bros - This is seminal, buy it.
3) Mario Kart - I'm still Double Dash to the core, but get it just for the online functionality.
4) Super Mario 64 DS - Hate. HAET. Prompted me to make
this image.
5) Metroid Prime Pinball - Not worth anything more than $5.
6) Animal Crossing: Wild World - Fun but wears out quickly.
7) Elite Beat Agents - Awesome rhythm game, may ruin your touchscreen.
8) Castlevania: Dawn of Sorrow - I loooooove Castlevania. Get it.
9) Castelvania: Portrait of Ruin - More of the same? If it's Castlevania... FUCK YES.
10) The World Ends With You - Decent and unique RPG with a cool battle system.
11) Yoshi's Touch And Go - Ummm... guilty pleasure. I got it for 5 bucks, so whatever.
12) Pokemon Diamond - You already have Pearl, same thing. We should have a pokeymans battle.
13) Metroid Prime Hunters - The single player is criminally retarded, but if you want to get the most out of wifi, it's more or less essential. I only played online a few times right when it came out, so I imagine nowadays everyone uses cheesy strategies and 1 character over and over.
14) Advance Wars: Dual Strike - Decent enough, but FW/AW will forever be inferior to Fire Emblem. I'd wait for that, instead.
15) Lunar Knights - Sort of fun until you have to grind yourself retarded (stolen phrase). Awesome music.
Upcoming
Castlevania: Order of Ecclesia - Castlevania fuck yes. Hawt female protagonist fuck yes.
Fire Emblem DS - It would be unspeakably criminal if Nintendo didn't translate this, but I wouldn't put it past them. Still, it's got a good chance.
Chrono Trigger - They better add some good extras, otherwise yawn.
"Unfortunately, the dragon only speaks in Napalm, a curious ancient language that you don't really need to speak to understand."