The following are known Gecko Codes for Fire Emblem: Radiant Dawn on Nintendo Wii (Wii).

Enable 300 items for all Chapters [g6flavor]
024C6962 0000012C
024C696A 0000012C
024C696E 00001C80
024C6972 0000012C
024C6976 00001C80
024C697A 0000012C
024C697E 00001C80

Equipped Weapon becomes Blessed when used in Battle Player's Turn [g6flavor]
203C1DB4 8069777C
003C1C41 00000090
E0000000 80008000

Make All Enemies Player Controlled, push 1&+ ON,1&- OFF v1* [g6flavor]
283D02FA 00000210
20666C68 705F6E6F
00666C84 00000000
E0000000 80008000
283D02FA 00001200
20666C68 705F6E6F
00666C84 00000001
E0000000 80008000

Make All Enemies Player Controlled, push 1&+ ON,1&- OFF v2* [g6flavor]
283D02FA 00000210
20697784 01000000
00697784 00000000
E0000000 80008000
283D02FA 00001200
20697784 00000000
00697784 00000001
E0000000 80008000

* If v1 doesn't work on your version of FE, try v2

Push A+B then end move to End Chapter [g6flavor]
283D02FA 00000C00
003C3A1C 00000004
E0000000 80008000