what is the longest and funest nintendo ds game ever

??? ??? ???

I'd say the Pokemon games. You can keep playing that for quite a while even after the main plot is done.

zelda games are usually pretty long

Rune Factory too~..
we can keep farming after the marriage anyway..but pretty boring...

Harvest Moon. It just rocks. It lasts forever.

Final Fantasy III? I've played on that for 150 hours..

Phoenix Wright you could play it for a very long time

Well, i agree with most of the people here, but pokemon is the one that stays fun.
Rune factory comes second.
Third is zelda because there is no 'afterward'.

I'd say pokemon for grinders....
Final Fantasy/Zelda for RPGers....
Phoenix Wright/Apollo Justice for people seeking good plot lines....
Tetris/Namco museum DS for classic gaming,
Possibly Custom Robo,Yugioh, or Advanced wars for competitive players....
Animal Crossing for interactive players, along with Rune Factory, or Harvest Moon...
Metroid for Action gaming
Mario Kart, Mario and Sonic, Super Mario... ETC for classic nintendo revamped gaming
Jump!/Bleach for fighters, maybe Assassins Creed, I gotta check up on that.
And we can't forget Professor Layton for mystery lovers... ;D