metroid prime hunters (fps, it's a good multiplayer game, but other than that it's not that great)
professor layton and the curious village (a very good puzzle game(over 130 puzzles) with a good story and nice animation)
phoenix wright ace attorney (one of the best games ever made, it's text based so if you don't like reading and paying attention when reading then you're pretty much gonna fail, you play a defence attorney and you have to help your clients win court battles by finding contradictions in witness testimonies)
apollo justice ace attorney (same as phoenix wright ace attorney, just 7 or so years after phoenix wright stops practicing law, so you play a new guy(apollo justice), but just as awesome)
new super mario bros. (pretty self explanatory, it's a nice game, a little easy but good nonetheless, does have some fun multiplayer options)
jump ultimate starts (japanese only, but one of the best 2d platform fighter games around with many charactes to choose, from many different anime/manga to choose from such as DBZ, one peice, naruto, bleach, black cat, bobobobobobobobo, etc.)
osu tatakae ouendan (a very fun rythm game, great music tracks, also one of my favourites, japanese only)
moeru nekketsu rhythm damashii osu tatakae ouendan (sequel to osu tatakae ouendan, japanese only)
elite beat agents (like osu tatakae ouendan, but with english songs, and a different story line, however a majority of the songs suck IMO)
megaman star force 1,2&3 (good game, but not as good as the battle netowork series, the style is a little similar)
megaman zx 1&2 (a very good 2d platformer, which is a similar style to the megaman zero series)
knights in the nightmare (a very unique game, it considered to be a try before you buy game, but is is a very good game, kind of like a strategy game, but a lot more different, you should definitely give this a try)
trauma centre 1&2 (surgery game, very fun, sometimes frustrating, you get to cut up patients remove viruses from the body)
lunar knights (if you played boktai on gba then you would probably like this, it's an adventure game, where you play as two characters who get their powers from the moon/sun)
time hollow(a very fun text based game, again if you don't like reading then you won't like this game at all)
rhythm heaven(nice rhythm game, but is a little difficult for beginners)
final fantasy crystal chronicles 1&2(good adventure game, but a little easy)
steal princess(haven't exactly gotten around to playing this yet, but i plan to once i finish knights in the nightmare)
legendary starfy(very cute platformer, but is also a fun game to play)
mario kart(good for multiplayer, but a little boring by yourself)
kirby canvas curse/power paint brush(not your average kirby game, in this game kirby is a ball, and you have to move him around by drawing lines so he can ride on, it's a good game, and is something different from the kirby series)
kirby squeak squad/mouse attack(pretty much the same as any other kirby game, but still good)
kirby super star ultra(pretty much the same as squeak squad, but with a different storyline)
mario and luigi partners in time(nice RPG game, the battle is turn based, but a little annoying when baby mario and baby luigi cry, which is alot)
mario and luigi bowsers inside story(not out in english yet, but i played it in japanese, and it is a lot better than partners in time, you get to play as bowser/giant bowser as well which is awesome)
freshly picked tingles rosy rupeeland(kind of a goofy game, but funny, the point of the game is to collect enough rupees to get yourself to rupeeland, it may not sound that good, but it is an awesome game)
zelda phantom hourglass(self explanatory, it's a zelda game, what more could i say)
advanced wars dual strike(a very fun turn based strategy game involving tanks, ships, troopers, and planes)
advanced wars dark conflict/days of ruin(just as fun, if not more fun then dual strike)
ninja town(a little like tower defence, you have to stop enemies going from one side to the other, by building ninja huts to get the ninja's to help you out)
bleach(one of the best/few fighting games on the ds, if you are into 2d fighters than this is your game for the ds)
rune factory 2:a fantasy harvest moon(cross between harvest moon and rune factory, you can farm your land and also fight monsters at the same time, you can also catch the monsters to help you fight other monsters/produce eggs/milk/wool, i do tend to like the rune factory:a fantasy harvest moon series a little more than the harvest moon series since there is more to do)
harvest moon ds/cute(good game lots of items to get, obviously still has the farming element to it, which i like)
harvest moon island of happiness(a more 3d version than all the previous harvest moon for handheld games, but it not too bad, but not that great either)
there are a lot more, but there is a word limit so i'll end it here.