The following are known Action Replay Codes for LEGO Star Wars II: The Original Trilogy on Nintendo DS (NDS).

Game ID: AL7E-B59F2403

Quick Stud Collect (In Episode)
a2101a2a 00000001
12104d9c 0000ffff
d0000000 00000000

Max Total Studs (In Cantina)
a2101a2a 00000001
02104d94 0098967f
d0000000 00000000

EPISODE CODES:

Episode Doors IV & V Unlocked
a2101a2a 00000001
72109218 0000900b
12109218 0000900b
d2000000 00000000
Enter any episode stage then exit to unlock doors.

All Episode Stages Unlocked
a2101a2a 00000001
121092ac 00007fff
d0000000 00000000

Free Play Unlocked for All Episodes
a2101a2a 00000001
121092b0 00007fff
d0000000 00000000

MISCELLANEOUS UNLOCK CODES:

All Characters Unlocked
a2101a2a 00000001
d5000000 ffffffff
c0000000 00000003
d6000000 0210925c
d2000000 00000000
a2101a2a 00000001
22109268 000000ff
d0000000 00000000

All Extras & Hints Purchased
a2101a2a 00000001
021092a4 1fffffff
d0000000 00000000

All Containers & Special Parts
a2101a2a 00000001
d5000000 ffffffff
c0000000 00000005
d6000000 02104dc4
d2000000 00000000
a2101a2a 00000001
22104dd8 0000001f
d0000000 00000000