types.txt

Acekard R.P.G. - .sav (same as raw)
Action Replay DS Max - .duc
Action Replay DS Media Edition - .duc
Action Replay DSi - .duc
CycloDS - .sav (same as raw)
EDGE - .sav (same as raw)
EZ Flash V - .sav (same as raw)
G6 DS Real - .0 (same as raw, different file format)
iEDGE - .sav (same as raw)
M3 DS Real - .0 (same as raw, different file format)
M3 Simply - .sav (same as raw)
M3i Zero - .sav (same as raw)
Ninja DS - .sav (same as raw)
R4 - .sav (same as raw)
Supercard CF - .sav (same as raw)
Supercard SD - .sav (same as raw)
TTDS - .sav (same as raw)
TTDSi - .sav (same as raw)

.duc (ARDSM): (500 byte header)

16 byte "game id" ("ARDS000000000001" for Action Replay DS)
46 byte game name (with "00" bytes in between each character, rest is "00")
18 byte separator (00, 17th byte "2E")
62 byte save name (with "00" bytes in between each character, rest is "00")
2 byte separator (00 00)
140 byte save description (with "00" bytes in between each character, rest is "00")
60 byte separator (00's)
23 byte game name (no spacing, rest "00")
6 byte separator (00, last byte 0D)
31 byte save file name (no spacing, rest "00")
1 byte separator (00)
70 byte save description (no spacing, rest "00")
25 byte footer (all 00)
normal save file

(With help from https://projectpokemon.org/home/uploads/monthly_2009_08/DUC_Structure.txt.f0af49605bdadbfa9536f1665990d0c5.txt)

.duc (ARDSME): (164 byte header)
4 byte header (00)
23 byte game name (no spacing, rest 00)
5 byte separator (A1 00 00 00 00)
31 byte save file name (no spacing, rest 00)
2 byte separator (00 00)
70 byte save description (no spacing, rest 00)
30 byte footer (00 x29, C0)
normal save file

.duc (ARDSi): (164 byte header)
4 byte header (00)
23 byte game name (no spacing, rest 00)
5 byte separator (A1 00 00 00 00)
31 byte save file name (no spacing, rest 00)
2 byte separator (00 00)
70? byte save description (no spacing, rest 00)
29? byte footer (00, last 2 bytes 08 C0)
normal save file