There are no dump text programs with the possible exception of kenghots FF3 one and deufeufeu's phoenix wright stuff:
http://www.romhacking.net/?category=&Platf...Go&title=&desc=
I think there is some stuff for pokemon as well.
US/EU games can use all manner of encoding, ASCII/unicode and the konami table (where all the lower case letters actually line up with the upper case ASCII) get a good bit of usage though.
Other than that you find the table the same way as every other system: find the text (nice/often fairly simple as DS roms tend to use a well documented file system or a simple abstraction on top of that with the files having obvious names).
Luckily emulation is pretty good which makes the next few steps easier.
Once text is located and assuming the font is not obvious (some games have the font in a
ASM hack/tracing. Harder than the following methods but it works all the time if done properly. Can also be used on compressed text that you can not easily decompress (most stuff is LZ compressed on the DS however).
A relative search can be performed (in most "text codecs" a comes 1 value before b) so you can search for that). Not all fonts are relative though (or contain dual tile encodings) and some are 16 bit with some relative searchers have problems with.
Corruption: alter a value and see what appears
Tied to corruption is brute force where every value is tested to see what comes up.
This is somewhat off topic though so can I suggest a new thread if you want to continue this discussion in any depth (not to mention it may benefit someone else).