You want Chrono Trigger? Final Fantasy Chronicles on PS1! Emulate it or play it over the PS3!
There are a lot of great games, but it's not for everyone (Monster Hunter, Burnout, Castlevania, Disgaea, Jeanne d'Arc, Loco Roco, Katamari Damacy, SSX, Silent Hill: Origins, Wipeout Pure, Syphon Filter, Metal Gear Portable OPs, plenty of fighting games, and a fair share of RPG and strategy titles). And once Crisis Core drops, you'll have a million FFVII fans squealing with glee.
I have to admit, I don't own a DS but I've never seen a game on the system that peaked my interest with the exception of Revenant Wings, and that went away after I saw the discussion about it here. Tactics A2 looks just like the first one, which I only played for a few stages before throwing it away in disgust. In fact, playing FFTA in comparison to FFT sums up what I think about DS gaming - it's a watered down version of a great game marketed to children as the key demographic.