You're so lucky you got me around. I'm the biggest "Hidden Gems for DS and Wii" guy there is.
Wii:
-Trauma Center Second Opinion and New Blood
-Zack and Wiki
-Metal of Honor Heroes 2
-Final Fantasy Chocobo Dungeon
-Blastworks
-Nights (kinda counts...it really didn't get that much love and its not bad at all)
-Geometry Wars Galaxies
-Battalion Wars 2
-Excite Truck
-Fire Emblem
-Endless Ocean
-Mario Strikers Charged (I know it sold a lot...but it doesn't get that much attention still...)
-Wario Land Shake It!
DS:
-Kirby Canvas Curse (Great game but nobody talks about it anymore)
-Contra 4 (Hard as hell, but Contra through and through)
-Tony Hawk's American Sk8land (First third party DS game to do online, and it did a great job...also just a solid game surprisingly)
-Crosswords DS (Simple, not THAT hard, and very relaxing and enjoyable)
-Meteos
-Elite Beat Agents
-Both Trauma Center games
-Viewtiful Joe Double Trouble (actually really good!)
-Etrian Odyssey 1 & 2
-KORG DS-10
...just off the top of my head.
